There are a few series on YT i enjoy. a number of them in my other fandom.
The .MOV series which is a totally NSFW parody series done in a Ren & Stimpy animation style. that I originally didn't care for for being so crude, offensive and over the top. But I found a new love and respect for after reading the guy's "Ask Jappleack" tumblr that ties into the series. Starts off in the same crude, vulgar style, but half way through switches tone so dramatically its jarring. it goes from a low brow answer-banal-questions-with-vulgar-images style thing (with true facts about apple at the bottom for some reason

) to a deep, serious and heartwrenching at times (yes, tears fell) fantasy/sci-fi story arc that leads into the final video. (the comments alone as it makes the switch are priceless. my favorite being on one near the end "How the **** did we get here?!"

)
"Two best friends play" is another. its two guys playing different games and recording themselves as they do it. they can be hysterical (again NSFW). their best ones though was a "mini-series" they called (and the title contains naughty words

)
where each day in october they did a different horror game. Hearing them trying to be all macho while they are clearly wetting themselves and in the end just freaking out was worth it. (there's also Two Best Sisters which is an animated parody of them)
There are several from Rooster Teeth. "Lets play", which is similar to Two Best Friends. "Red Vs Blue" which is a halo parody series that, like "Ask Japplack" (though not vulgar), takes on a more serious tone as it goes along. it actually becomes a pretty good Sci-Fi series. "Fails Of The Weak" which showcases fan submitted bloppers from halo fans.