Just an FYI but it's pretty easy to do in KDE, in fact I believe they even have a package to help set things up for you. After quite a bit of searching and rummaging through my brain I found Animated Video Wallpaper
I know that probably won't help you but it may help fellow KDE users. I did find a topic on the Linux Questions forum
that may help with some information from just last November. Again it's for KDE but the info should translate fairly easily to your DE.