"TEXTp is the result of months of intense transcoding efforts by our engineers, who toiled for weeks to ensure that a large chunk of videos on the platform could be reduced to their most basic elements. By replacing the images in the video with a series of letters and numbers, the videos are far less taxing on our system -- and have the added benefit of promoting literacy!"

To check this out:
http://www.youtube.com/watch?v=Q_xVXQCrPxQ&feature=featured&textp=fool

You can also append &textp=fool to most video URLs to test it out.

For every person who selects TEXTp and keeps it on while you watch a video, you save YouTube $1 a second, resulting in potentially billions of dollars of savings for us. So if you care about YouTube, you’ll use TEXTp today

PS. If you missed, check this: http://i41.tinypic.com/2wntzkk.png