How can I sync movies from iTunes to my iPad?
The problem is that when you buy a movie it is not immediately downloaded to your machine. You have to explicitly tell iTunes to downloading by going to your "Library", selecting Movies from the left panel, right-clicking on the new movie and selecting "Download". Once the download starts you will see a screen like this:



The button next to the search box in the upper right will show the download status. Once the download is complete, click sync button which is the small rectangle next to the media type combo box in the upper left. (This button is right below the "Account" menu in the screen shot above.) Your new movie should appear grayed out (as shown in the screenshot below). Then, select "Movies" from the left hand navigation pane (iPad submenu), make sure that the checkbox for syncing your movies is selected, and press the Sync button to start the transfer to the iPad.