As a few of you here have requested this feature, I could use some input...
At the moment, after 5 seconds of inactivity, the movie preview (if available) will play in place of the screenshot (Artwork # can be specified). Here's the questions:
1) Is 5 seconds ok, or should I reduce it (maybe 3 seconds)?
2) What should happen if you move off of the game, when the movie preview is still playing? Should it stop immediately and display the screenshots of the newly selected game(s), or continue playing until finished?
3) What should happen when a movie preview has finished? Maybe cycle between screenshot and movie?
I could make all these configurable, but I'm not sure it's worth it (?)
And before anyone asks, I've done intro/exit & screensaver movie support 
Here's my opinion:
When you select a game you want it to show right away ... Using a delay doesn't seem logic ... it's as if you wait with a blank screen before showing the snap ... to me it doesn't make sense so as for questions number on: No delay. Show in this order:
1st movie
2nd snap (if movie doesn't exist)
3rd alternate (if snap doesn't exist).
For the second one ... I don't want to wait for a 10 or 15 seconds movie to finish, when I'm looking for a game so:
- Ends right away and starts the movie for the selected game (after one stops the up or down movement when searching)
For the 3rd one ... cycling !!!
Regarding config I think you don't need to wast you precious time on that (regarding this subject). Why ? In my opinion if you want to display the movies you will not want the delay. If you don't want, simply you don't place them on the specified directory.
I have posted some time ago a link to a fe that uses this feature:
http://www.arcadecontrols.org/yabbse/index.php?board=3;action=display;threadid=18312You may want to have a look ... it may give you some aditional ideas ... this machine is working on an arcade shop near by ... it's really nice the looks of the movie. At first I thought it was the game running, but I think that's not possible ...
Anyway ... hope this helps to improve your great FE ...