Windows Mobile 5 did not seem to have an easy way to have YouTube mobile videos (3gp files streaming over rtsp protocol) play to your phone.
However with Windows Mobile 6 Professional and HTC’s “StreamingPlayer” software – playing YouTube Mobile videos, at least through PIE (Pocket Internet Explorer) is easy.
If you don’t have HTC’s StreamingPlayer – check here. After installing the software, you may also need to modify your registry in order to allow rtsp streams to be opened by the player. Here is a link to the registry entries you need to make – again courtesy of XDA-Developer’s forum.
Save the above text to a .reg file, and import to your device (for example, using RegEdit for WM6)
Hopefully if all went well – when you visit http://m.youtube.com, and click play video, the HTC player will launch and play the video. After the video is done the player will automatically close and bring you back to the browser.
Note that for the above to work, you need to either have wifi access or an unlimited data plan for your wireless account – because streaming video WILL take up a lot of data!
Main Youtube Mobile Screen on WM6
Video Page on WM6
In Landscape mode – you can see the quality of the video is not that great even over WiFi
For another great article on getting this working, check here.