WMV AVI MKV RM RMVB XVID video file types are not supported by Apple iPad natively. What to do? You can convert them to .m4v, .mp4, or .mov file format which supported by Apple. However, it is not the best solution if you have lot of unsupported video files. Try the simple way, get a 3rd party video player that can support multiple video formats. Personally, I tested OPlayer HD for iPad. And it is working on RMVB video file with frame skipping enabled. Not 100% smooth but better than cannot watch at all.
How to play Real Media (rm, rmvb) video with HTC HD2? Which video player can play real video smoothly in HTC HD2? Well, I tried a lot of media players like RealPlayer for Mobile Devices itself. It cannot load in HTC HD2 at all. Some guys copied video player from Toshiba TG01 also does not do the trick. I end up convert rm, rmvb video to mp4.