I've been frustrated for a while with the fact that YouTube sends the crappy FLV videos to Blackberries through the browser instead of the high-quality MP4 versions of the video that you get when you use an iPhone/WinMo/Android device.
I've found a workaround... it's a bit of a pain, but it works.
Navigate to the to the YouTube page of the video you want to watch, using the BB browser.
Hit Menu, Page Address, and copy the page address to the clipboard.
Menu again, 'Go To...'
Paste the youtube address, but change the m.youtube.com part of the URL to youtubekeep.com (make sure you remove the m.).
So the address should go from this: http://m.youtube.com/watch?v=qnlYhDE3CT8
to this: http://youtubekeep.com/watch?v=qnlYhDE3CT8
Youtubekeep.com is a site that allows you to download YouTube videos in several formats.
You'll get a page that offers you a few buttons to click to choose whether to download it in standard FLV, mobile 3gp, or mp4. Choose mp4 and a download link will be generated to the right. Click that, and you'll then get the option to either open or save the file. The quality is awesome!
I have tested this on the Tour.
Now... the challenge is for one of you intrepid developers to make a YouTube app that gets the mp4s natively without having to go through this rigamarole!