"Very often, I get people asking me if there is a way to play flash files on a Pocket PC [...] The good news is that this is now possible if you use TCPMP. A new plugin is available at http://sourceforge.net/project/showfiles.php?group_id=196939. That will let you download Youtube video directly to your PPC and play the flash file without conversion."
Playing flash video content on Windows Mobile has always been an iffy proposition - the format used by YouTube and other video sharing sites was just not supported...until now. I've tried out the plugin from the link above, and it really does work (I tried the video of Judie's
HTC Advantage unboxing). A couple of caveats though - this is a 0.1 release, so try at your own risk; and it requires TCPMP. Installation is simple enough, just put the two *.plg files in your TCPMP folder and start TCPMP. You can either use the included downloader for direct downloads of videos to your device, or just transfer any *.flv files that you've already downloaded to your computer to your WM device. Enuff Said - try it!