I am curious why you think zero forward speed?
No apparent backwards bending anywhere, the wings are completely flat yet still "connected", no apparent disturbance immediately behind the aeroplane etc.
In a down draft you'll be trying to climb, which is why the nose would be up. If you stall, well, that is just bad piloting, but if you didn't and you hit the ground it would be in a nose high attitude.
15-20 kts shouldn't give too many problems around mountains, especially if clear of them by >1000', it might be a bit bumpy but I wouldn't have thought that there was anything nasty enough to cause this crash.