Draco Malfoy in A Very Potter Musical is this trope through Flanderization of his original character and he's surprisingly more canon than Draco in Leather Pants. He's a bullying coward who believes the only thing keeping him from being the coolest kid in school is Harry and is constantly trying pose and failing spectacularly. He does shape up and join the good guys later on in the show but he's still got the ego.
Linkara the character is this, berating his fans for asking his opinions on comics. Of course, out-of-character, an "I love you guys" is very quickly added. Lewis himself admits to having an ego, but he makes sure to refine his skills in order to stay on Awesome Ego territory. One arc even focused on his arrogance being the first step on the path to a Face–Heel Turn.
The Nostalgia Chick, Dr. Tease and The Makeover Fairy are all this, although the actresses - Lindsay and Elisa - are nice, down-to-earth women. Like Critic, the Chick's self-esteem is pitifully low and she abuses people to make herself feel better.
Matt in Two Best Friends Play during the Marvel vs. Capcom 3 video. He had played the game beforehand and thought he would kick Pat's ass. He did at first, but Pat eventually learned how to play the game and did much better than Matt, and showed that he actually knew who the characters were. And that's not taking into account the incredible level of humiliation they both suffered at the hands of an unnamed third guy (later known as Woolie), who was far more intimately familiar with the game than either of them.
In general, the Matt/Pat dynamic often has Pat acting superior to Matt and comically lording it over him or otherwise deriding him in some way, desptite it being shown on numerous occasions when the sitiuations are reversed that there's no significant difference in abilities.
"When will they see that their crappy little show would be so much better if I were acting in it? And writing it? And directing it?"
Sonty Mick from These Web Comics Are So Bad. He constantly refers to himself as an "award-winning" critic, interrupts his reviews to describe his personal life, and encourages readers to send in fan-art of him. Sometimes he even claims that he could vastly improve comics by inserting himself into them.
The Sharkasm Crew divides itself into smaller crews for Crew Battles. AMPS is easily the most outspoken about their confidence in winning said Crew Battles. They never do.
Jim Sterling, at least the character with the same name as him he plays in Jimquisition, ends every video with "Thank God for me." He regularly says things like "there you go, I have, once again single-handedly saved the video game industry." Although, it has to be noted that when standing on his podium next to the V For Vendetta-style background much of what he says is firmly in Sarcasm Mode territory.
Played for Laughs in Third Rate Gamer. He parodies how little credit The Irate Gamer gives to other people in his work, and often writes very self-centered things about himself in the credits. TRG also thinks the "Coolness Meter" in Cool Spot should start at 100% for him, because he's "The fucking Third Rate Gamer!" Still Played For Laughs, of course.
John (reading out a letter): Dear Dredge, I'm a big fan of the Nothing To Do With Anything Show, but feel that the main supporting actor, Greg Haiste, is somewhat underused. What do you propose to do about it? Yours hopefully, Greg Haiste. Well Greg, we've taken everything you've said on board - and completely dismissed it.