Yes
you use GameMode.playVideo(filename)
where file name is the path inside your mod_asset folder to your video.
The video must be encoded with VP8 (see
http://en.wikipedia.org/wiki/VP8) , the last time I checked the beta version of handbrake could encode into VP8 (see
https://handbrake.fr)
Videos do not play inside the editor, if you want to play the videos from the original game you need to point to them (I don't know the filepath or filename)
if you leave GameMode.playVideo outside a function it will play when you start your dungeon from the game.
You can also nest GameMode.playVideo inside a function and call that if you want to play cutscenes during the gameplay itself, and you can call GameMode.completeGame(filename) for the ending.
Hope that points you in the right direction.
Skuggasveinn.