In the "Let's Play" Happy Wheels episodes, one level, "It Keeps Happening!" tormented Nova to no end, and he eventually had to give up and move on. For the 100th episode, he tries the level again and FINALLY beats it. What makes it so awesome? After dying so many times in the previous videos, he manages to beat it on the FIRST TRY.
In the same video, he replays another level that he never finished. He beats that one on the first try as well.
One not for Nova himself, but for Immortal HD. While playing Dark Souls II, Nova struggles againt The Last Giant, dying many times and getting nowhere near beating him. Finally, he decides to call in the help of Immortal, who's much more experienced with the game. Nova summons Immortal into his game, and they take on the boss together. Immortal proceeds to take away about 80% of The Last Giant's health bar singlehandedly, then suddenly stops fighting and tells Nova that he can't just rely on others to fight for him, and he has to finish the boss himself. Nova is so flustered that he ends up killed by the boss after coming just a couple hits short of depleting it's health completely. This also happens to be the event that causes Nova to Rage Quit.
When Kevin saves Nova and Immortal from someone who was holding them hostage in the first episode of Gmod Dark RP by punching him while they got away.