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: Aka 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.
- BlastphamousHD TV: he also has a more popular gaming channel called BlastphamousHD Gaming note
- BSL Reaction Asylum
- FandomReactions: Originally a six-girl but prominently Four-Girl Ensemble known for their cheerful, snarky, and Hot-Blooded personalies 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.
- The Fine Brothers aka React: The channel 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 channel's popularity was most likely what inspired all other reaction channels on Youtube, even though none of them follow their exact formula.
- 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 aka 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.
- Lost Pause: Noble frequently reacts to compilations of anime-based Vines, "cracks", and memes.
- Mamba Jumbo
- 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.
- Tyrone Magnus: Aka The Black Viking aka BatMag aka 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.
- 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.
- 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.
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 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.
- 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.