The problem is that you still need a GPS moving map which shows you where you need to glide to, in a very clear manner.
I didn't watch the whole video above (it's a simulation, after all) but I recall there was another similar video going around where a Cirrus pilot used synthetic vision to get down through IMC, following an engine failure. Maybe it is the same one? SV should be very good for that purpose. You just need to be high enough above the terrain to start with
I have not been able to find a piece of software which would deliver SV on the winXP tablet I fly with, which is why I fly with that stuff I posted a pic of. It was laboriously generated from the Google Terrain map server, using a piece of software whose developers got sued (and otherwise threatened) because it hogs the server bandwidth so it no longer officially exists in that version.
One day, this thing might save my life.
SV does exist; my son had worldwide SV on X-Plane a few years ago. It involved about 6 DVDs with the NASA SRTM data. But that implementation was not viable for in-flight use. One needs something which you just turn on and off it goes.