From the site:
"This website is designed to provide an accessible version of the popular video-sharing website YouTube. In addition to traditional accessible design practices such as semantic, well-structured markup, high-contrast colour schemes and standards compliance, newly-available technologies such as WAI-ARIA have been implemented to allow users of assistive technologies to benefit from rich functionality such as dynamic page updates.
Unlike the regular YouTube site, videos here don't auto-play. You can start them by hitting the Play button or, alternatively, by using a keyboard shortcut. The combination Alt+Z will play a loaded video (or pause one currently playing), while Alt+X will skip 15 seconds backward and Alt+C will skip 15 seconds forward. To begin viewing videos, use the search form at the top of the page.
Click this link to visit the Accessible Interface to YouTube: http://tube.majestyc.net.