you need a sd card installed, not the autonooter card, or if thats your only one, reformat it first.
In the market download astro file manager. In astro go to the menu>app manager. Check the box next to the YouTube app then tap backup at the top of the screen. After backing it up, uninstall the app (nook color tools or astro will work) then use astro app manager to reinstall from the SD card. (Thanks to AintSkerd for this tip)
im considering installing the hi def youtube, but i will only do it knowing i have a backup of the original on my sd card from when i had the same problem. ive also heard of others using titanium backup to clear the app data for youtube with success for this problem, but have no experience doing that myself.