http://www.youtube.com/t/terms_paycontent

"YouTube allows you to view certain video content ("Pay Content" in other words, "copyrighted content") for a fee by streaming or downloading (as applicable) that content through YouTube for a specified price (the "Service" in other words, paying for videos). The Service includes YouTube Rentals and any other YouTube service or feature that makes such Pay Content available to you via YouTube. Your transactions and any other use of the Service and Pay Content are subject to these YouTube Pay Content Terms of Service ("Pay Content Terms")."

Essentially, big companies can charge you to watch videos, and can place price tags on other peoples videos.
Also, it apparently will only accept pay in some areas, and in the areas it doesn't, the videos will be blocked off entirely.