TheRunawayGuys, NintendoCaprisun, Mangaminx, SlimKirby, TheGameStation, TheWarpZone (check out my fansite TheKarpZone(yes, it is magikarp themed)) also some smosh, tobuscus, vlogbrothers, scishow, hankgames, crashcourse, dftba.
Pokemon in Real Life by Smosh are hilarious. I wish they would do #5 and beyond. I also like Zelda Dungeon's channel. I usually end up watching my favorite bands or songs at the time. Sometimes I wonder in to weird stuff like botflies in the head from a trip to Costa Rica. Then I know it is time to log off.
I have been watching the Super Paper Mario walkthrough by Chuccaaconroy. I already played this game many years ago but the guy is funny and cracks me up. I do this often only watching the game because of the funny comments people make while playing the game
-LP's (The reason why is because in case I missed anything from a certain checkpoint. I can write it down and play whenever I have the chance. Also, some of the LP's are pretty funny, so I'll mostly watch it for the humor too.)
-OST's (I don't know why. But, I mostly listen to them whenever I'm cleaning or surfin' online.)
-Trailers (<3 )
-Cutscenes from videogames (Same reason. Sometimes I'd rather watch a certain scene instead of opening my PS3 and playing up to that point.)