This is my first tentative proof-of-concept test playing around with the idea of integrating external video in an inworld Second Life machinima. It uses the new Media Sharing functionality that allows enables the flexible and interactive display of media directly on a prim. The "skull speaks" video was set as the media texture and then the Second Life screen was shot with a handheld iPhone and edited on the phone using Vintage Video Maker and ReelDirector.
There's great potential in combining various types of external media within a realtime machinima capture. I hope to spend a bit more time to put together something a bit more ambitious in the very near future.