It's kind of like Let's Play, but for videos. The host (usually called a "reactor") watches a video that they've never seen before, and we get to witness their first reactions to it. Some reactors also like doing predictions before they watch the video, or a quick analysis afterwards, but the main part is the reaction itself.
There are several channels on YouTube dedicated mostly to reaction videos (called "reaction channels"). They gather small, but dedicated fandoms, who enjoy watching their favorite reactor's reaction to different videos. Some of these reactors craft a specific persona they play on-camera, to make their reactions more interesting to watch. Their video choice usually involves a movie trailer, music video, viral video, rap battle, or Vine compilation.
Other YouTubers sometimes also make Reaction Videos; "Reacting to my old videos" is an especially popular theme.
Some reaction channels:
- Akasan: A.k.a. The Black Man in Japan. A red-dreaded black man living in Japan, he likes to react to movie trailers, especially superhero-related ones, and K-Pop music videos.
- BSL Reaction Asylum
- Blind Wave
- Drowning In Fandom Feels: Featuring Jaclyn and Marcella, two best friend Genki Girl's who share a room. They are very emotionally invested in their shows and like to ship a lot. They also each have a dog, Mickey (Jaclyn) and Happy (Marcella) who occasionally make funny appearances.
- Etika: This individual was well-known for his very hyped-up reactions to Nintendo game announcements. Tragically committed suicide in June 2019 after several noted manic episodes that first began in October 2018, leading to much mourning from the Internet.
- FandomReactions: Originally a six-girl but prominently Four-Girl Ensemble known for their cheerful, snarky, and Hot-Blooded personalities and analysis of episodes they watched, as well as for their occasional cosplaying. It had two Spin-Off, B And B Videos and AlectricBritSmash. The former was founded by the two other original cast of FandomReactions, while the latter was founded by one of the previously mentioned duo with her boyfriend not too long after the girls parted ways. In both cases, the two spin-offs mentioned were founded by the twin sister of FandomReactions' leader, making the videos sister shows in both literal and figurative sense.
- Freelancer Amber is a reactor who reacts to mostly Rooster Teeth content like Red vs. Blue and RWBY, and Death Battles [[note]] Technically also Rooster Teeth content now, but not originally [[\note]]
- Gattor Martin: Hosted by Gattor Martin and his friend and roommate Koollee. One of the first reaction channels spawned by React's popularity. They mostly react to movie trailers and viral videos.
- Jinx a.k.a. Star So Silly: Mostly known for reacting to Vine compilations every day, in what he calls his "daily dose of Vine". Also one of the first reactors who reacted to all Epic Rap Battles of History videos and offered opinions on who won and why. He reacts to other kinds of videos, too.
- CJ So Cool: As spin-off of Jinx' channel, hosted by his brother CJ So Cool, and occasionally featuring CJ's girlfriend Royalty. They usually react to the same kind of videos as Jinx.
- Kyuujin Reacts: Hosted by a female cosplayer duo from Quebec, known for their range of emotional reactions and their in-depth discussion after screenings. Generally tend to react to anime, but have branched into live-action series like Breaking Bad.
- Lost Pause: Noble frequently reacts to compilations of anime-based Vines, "cracks", and memes.
- Mamba Jumbo
- The Normies: Hosted by a group of friends who frequently perform skits based on what shows they're reacting to.
- Rarity Dash is one of the most prolific and popular MLP reactors, who started with a reaction to the second installment of the Equestria Girls spin-off series before moving on to reactions to fan works and the show proper starting with season five and has since expanded to covering other Western cartoons like Adventure Time and Steven Universe and anime like Miss Kobyoshias Dragon Maid among other things.
- React: A series by The Fine Brothers that started back in 2010 and inspired most other YouTube reactors. Their videos feature several people reacting to one video, and then giving their opinions on it. The reactors are grouped together either by their age (kids, teens, adults, elders) or celebrity status (YouTubers, celebrities). This series' popularity was most likely what inspired all other reaction channels on YouTube, even though none of them follow their exact formula.
- Reaction & Review
- The Reel Rejects: Hosted by Greg Alba (formerly Ryan Right), each video features him pairing up with numerous guest stars. They mostly react to movie trailers, or videos related to movies. Greg's jokes usually revolve around Self-Deprecation and Camp Straight, but he also can provide insightful commentary.
- Renegades React: A group of nerdy friends that react to all kinds of videos. Notable for lengthy discussions and/or rants they have after watching the videos, which can prove quite amusing.
- Sesskasays: Best known for her cheerful, pleasant personality and her in-depth analysis of episodes she has watched, as well as her range of emotional reactions to various shows. Quite popular among the Doctor Who community in particular for her attraction to Matt Smith's Eleventh Doctor. She also hosts an annual event called Doctor Who December, which features her reacting to episodes old and new, as well as showing viewers how to cook and decorate their house with Doctor Who-themed Christmas decor.
- Smurf Vlogs is a YouTuber who makes a variety of content, but he's most well known for his reactions to Disney movies and series and his MLP reactions, among other things.
- Torchwood Boy: A redheaded British reactor best known for his Campy, pleasant yet snarky personality and his in-depth analysis of episodes she has watched, as well as his range of emotional reactions to various shows. Quite popular among the Doctor Who community (he got his username from a Doctor Who spin-off after all) and has made Crossovers.
- Tyrone Magnus: A.k.a. The Black Viking a.k.a. BatMag a.k.a. The Black Kryptonian. Among all of the reactors, Tyrone Magnus has the most recognizable persona: a boastful Large Ham with ironic undertones of Scary Black Man. He usually reacts to movie trailers and viral videos, but also sometimes reads out news articles and reacts to them, or provides advice to his viewers.
Examples of this trope in media:
- One episode of The Tonight Show featured Jimmy Fallon having The Roots watch a trailer for Fifty Shades of Grey, with the twist that he edited a Screamer Prank into it.
- Mick Foley shares an anecdote in his second book, Foley is Good, where ABC News showed him a video of some backyard wrestlers and asked for his reaction. Having been tipped off beforehand that they were going to show him some pretty horrific stuff, he said, "That looked like a lot of fun...but I have a feeling there's another video you're going to show me." They showed him the second video, and his response was to say that the kids in the video were being very unsafe and he did not condone any of it. When they broadcast it on TV, they showed the second video but his first reaction, "That looked like a lot of fun!"
- ClickHole parodied this trope in a video where people watch the opening sequence of Up, but instead of being affected by the tragedy depicted in the movie, the viewers make Captain Obvious comments.
- During E3 2019, DK Vine posted a video showing their reaction to Banjo-Kazooie being announced for Super Smash Bros. Ultimate during Nintendo Direct. The video continues further to show their reaction to the follow-up announcement for the then-untitled sequel to The Legend of Zelda: Breath of the Wild... or lack thereof.
- The Ultra Fast Pony episode "Ponyville Noire" has an Arson, Murder, and Jaywalking gag where a character's petty crimes are listed: "street robbery, vandalism, react videos..."
- Played for Laughs in JEM REACTS - to the new Jem And The Holograms Trailer. In it, cosplayers roleplay as the Jem characters and react to the trailer of the In Name Only Live-Action Adaptation Jem and the Holograms.
- Scootertrix the Abridged has a side series of Celestia and Luna React videos, where those versions of Celestia and Luna give in-character reactions to My Little Pony toy commercials and fan animations like "Lullaby for a Princess" and "Let It Go (a Nightmare Moon parody)". (The voice actors had seen the videos beforehand and broadly planned most of the jokes, but the actual dialogue was improvised.)
- Family Guy:
- There was a promo where Brian shows Stewie some clips on YouTube and records Stewie's reactions.
- In a Cutaway Gag, Brian shows Stewie "2 Girls 1 Cup" and films Stewie's reaction. At first, Stewie is horrified, then decides to search for a two guys version.
- In the Steven Universe short, "Steven Reacts", Steven reacts to the newest episode of Crying Breakfast Friends, parodying Steven Universe and its viewers.