I'm curious what they're "extremely" mad about... AFAIK YouTube is a poster child for the RIAA as a massive cash cow. Google auto-detects copyrighted works and all uses of a copyrighted content in a video, even fair-use (including background-noise e.g. having the TV on in the background when you video your child's first steps) give the RIAA a payback. Certainly they're still vigilantly sending take-down notices for content they want removed, but... by-and-large, it's gotta be dump trucks of free money to their doorsteps...