I can't watch the YouTube vid on this computer, but I guess this is the one of the morons who decide to go scud running up a valley in the clagg?
If so, then GPS is probably to blame for saving their lives, and the fact that the GPS dB doesn't have trees in it can hardly be blamed on GPS! GPS terrain dB has a certain resolution and is mapped from space, so although it is in general good enough to avoid dying, when you decide to do something really stupid then all bets are off. Not sure where synthetic vision gets its data from but it is damn accurate with regards to runway positions etc....
I don't think they had synthetic vision as this video's been out for a while.