That was entertaining and en-wait for it-lightening. And did you see the chemistry between the leads? Sure, "Timmy Gordon" didn't have any "dialogue" or "live-action scenes," but even New York Governor David Paterson could see that heat*. But that red-hot fire is made from a mixture things called "acting" and "mutual respect."
We are professionals (fine, she is, I'm just unconventially handsome). And we care too much about the "craft" to let anything from "out there" to come "in here" (and, if I'm not mistaken, the converse is also true). Why ruin a sure thing scene partnership on a hit-or-miss proposition like dating a performer (ahem, Brad Pitt and Angelina Jolie).
After watching "Facebook Manners And You," YouTube user xxjungahfantasyxx had this to say, "haha that was great. and its good to see those two back together!! i loved them in love u." To the point, thoughtful eloquent. Lots of people feel that way, I'm sure. Wouldn't it be heartbreaking to see some off-camera ish come between them (looking at you Justin Long and Drew Barrymore)? It's amateur and it builds on-set tension (the stress on Dexter has to be palpable since Dexter married Dexter's sister in real life).
The Ghost Whisperer (which I have not seen) can't be improved by Jamie Kennedy and Jennifer Love Hewitt dating in real life (I would be on easy street if I was as good-looking as Jamie Kennedy). The only show that appears to be improved by off-screen hanky-panky is Gossip Girl and it's only because that show is bulletproof.