for my new curve 8900 i'm using the bbvideo creator (
Seabyrd Technologies - Blackberry Video Converter)
intro of the app: only for pearl and 8800
but - you can manually change the screen-size in the video-settings.
(the curve needs 480x360)
youtube with curve no problem - with keepvid
KeepVid: Download and save any video from Youtube, Dailymotion, Metacafe, iFilm and more! and bb video creator:
-copy the youtube-url of the video.
-paste into keepvid and click 'download'
-in keepvid: save the file as *.flv or *.mp4 with right-click
-open the *.flv or *.mp4 in bb video creator
-change your screen-size manually in 'video'-settings (bold 480x320)
-save and convert
very simple and the function: its great!
(dvd and curve: also no problem with the bb video creator)