Although his nose does look flatter in the most recent video, I can't tell because of the poor quality of the shot and his distance from the camera. I note, however, that age can cause the nose, ears, eyelids, etc. to droop and sag, and I suspect that OBL has aged quickly over the last few years if he is in fact alive. Heck, for all we know he fell off an ass and broke his nose while traversing the mountains near Tora Bora. Another possiblity -- again, if he is in fact alive -- is that he deliberately broke his nose to disguise his looks, like a poor man's plastic surgery.
The bottom line is that I can't tell one way or the other from the video.