Diki, I think you're getting too much sun. Have you seen the state of the art DJs? They're not too far away from this kind of stuff now - video, live cams, big screen monitors, karaoke - the works.
You or we can be music purists and insist the music be played, but haven't we already started down that road with arrangers, SMFs, mp3's, lights, etc.? All it takes is for one musically inclined go-getter to start something like this and the DJs will be out of work; this guy will be taking all the business. This could be the entertaining musician's avenue back into the mainstream of weddings and parties that pay real money.
I'm not saying it's an idea for me, but the commercial applications are vast. Mark my words, somebody soon is going to be doing this... if he isn't already.