I'm unable to move mp4 videos from computer to my iPad. I have imported them into iTunes, but still I'm unable to sync my iPad.
You must check the status for automatic synchronization of movies in iTunes. Follow these steps:
In the Library, click on the "Movies" tab and verify that all movies that you want to transfer to the iPad are present. If you want to add some more, click File> Add *File to Library "and select the movie format (.Mp4,.Mov)
Now connect your iPad to PC
Select it in the "DEVICES"
In the right pane, click the "Movies" tab > "Sync movies" which lists all your movies stored in your iTunes library.
Check then "Automatically include" option and click "Apply."
For.Avi files should install OPlayerHD Lite on your iPad