Hope this helps
YouTube videos should not be a problem, you must have a connection to the Internet by wi-fi or 3G (youtube on 3G can get expensive), tap on the YouTube icon on the iPad.
To preview films on iTunes you must have internet connection and an account with iTunes ( they will want your credit card number).
You can also load videos from the computer that you use to sync with iPad. The videos must be MP4 or converted to MP4 format. In detail: to load the video into iPad ( I use windows 7); connect the sync cable, ITunes should start on your computer and sync to iPad,after sync is finished under Devices click on your iPad icon, on the top bar click on movies, make sure Sync Movies and automatically include are check on. On left side under "LIBRARY" click on movies, reduce the window for iTunes. open the folders where your MP4 video file is and right click and drag it into the iTunes movie window, select copy, then click on "Sync" icon bottom left. after sync is finished the video is in your iPad movie icon and should play.
Best of luck
Bruce
I do not know what BBC I player is and can't help you for it.