YouTube - Official You Tube app for Windows Mobile | 1800PocketPC
There are many apps that supports youtube on windows mobile and some of them like WebVideoDownloader also allow you to download the videos on to your device. Now Google has released an official client for Youtube that supports many Windows Mobile devices. To get it visit [ http://m.youtube.com ] from your device. Be careful if you dont have a good data plan as this app can be a very high intensive data hogger.