A hilarious addition!
This is a very creative use of those otherwise crappy computer voice synthesizers. It's silly, it's poignant, and it's un-PC! What else could you want in a flash? I'm sure Stephen Hawking would be so very flattered at your touching tribute. One would almost shed a tear at those moments where Stephen's voice synthesizer struggles through a verse. As for the bonus material, I quote my sister as saying "corniest joke ever" ;)