Make sure the iPad is connected and iTunes has opened and performed the back up and sync (if you have it set to do so when connected)
Click your iPad down the left
Click the Movies tab along the top of the summary page
Ensure the movies you want are ticked to sync.
(you may need to fiddle with the drop down boxes to ensure it's set to sync over what you choose and not choose for you what gets sync'd)
Hope this helps, and doesn't come across as patronising.