iTunes won't automatically bookmark your video files playback postiton so you can resume where you left off. You need to right click on the track, select "get info" and check "remember playback postion" under the options tab. Unfortunately there is no way to do multiple tracks at once. Here is a c# code snippet that takes the selected items in the itunes browser window and sets the "remember playback position" to true. You will need to add a reference to the iTunes type COM library.