It's seem like the mobile site m.youtube.com is all but history now.

Instead you need to use this new Iphone layout version.
http://m.youtube.com/?app=m

This is the thread that I used and enjoyed the most for playing YouTube videos.
http://talk.maemo.org/showthread.php?t=84669

If you have the patience and time, you can always use this site as well.
http://www.clipconverter.cc/

Set the conversion to .Avi, max out the video bit rate to 768 kbps, and then convert.

From my months of using that site, I have found it's best to do this after 12 am EST where it can download YouTube videos up to 50 Megs per second.

In the morning, afternoon, and evenings it can be quite sluggish at times.

Anyway, I don't care at all for the new mobile YouTube page and it was enough for me to own a Nexus 10 tablet for watching videos.

Best of luck.