Sorry if this has been posted already, but after 33 pages I've lost track.

Here's how to get HD videos on YouTube to work on the NC. (Shamelessly lifted from nookmods)
- Uninstall your current YouTube app
- Download HDyoutube.apk from here: http://db.tt/y5vVvI2
- Using Root Explorer (or file manager of your choice):
- - Rename to youtube.apk
- - Copy youtube.apk to /system/app
- - Set permissions of youtube.apk to rw-r--r--
Now your YouTube app will play HD videos on YouTube.