Keeping this short with hopefully more to be added later as it's 1am and I just feel compelled to write this (I blame the sugar).
I ADORE User created stuff. I use the word 'stuff' cause I'm not referring to user maps or anything. I'm talking about outside game content.
Check out
Portal - The Device has been modified.
This takes the voice files from the game Portal, mixes them up with music to it and you know what? It's incredible. I am addicted to this tune. Thank you
Invicticide for posting it.
Or how about -
The Craft of War: Blind Made using the models from World of Warcraft.
Or
Megaman II - Dr Wily's Castle A rearrangement of a NES game's song on guitar.
Unofficial WoW patch trailer Another Warcraft related vid, the idea is if a patch was turned into a video, what would it look like?
Here's another -
Mortal Kombat (NB: Possibly Not Safe For Work)
I'm continually astounded by the quality and overall epicness of user made stuff. The thing I enjoy most about Youtube is user made videos, trailers and music.
Anyone got any to share?
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Update!
Portal: Day in the life of a turret Haloid