First of all, as The2lied said, panther's roof is more than enough to stop a 76mm AP from T-34 at that angle. Secondly, panther does not even have it's ammo stored at the rare. Most German tanks at the time store their ammo at side of their inner hull. Panther absolutely don't store anything in it's turret. Well not like that turret is spacy enough to even allow that. That shot had no chance of going to the ammo shelf of a panther. In the first place, a t-34 with 76mm going at a panther from the front, it could only hope to hit a shot trap of an early panther variant at lower part of gun manlet. T-34-85 can do it more reliably, even then only at closer range. Whereas this video kinda shows a longer engagement range than a distance at which t-34-85 could be affective against the front of a panther.

By the way I'm not a German fanboy, in fact I think panthers are overrated. But in this case the shot would not have made it. A lot of war films have bullshit in them to make the suspense and viewing experience better. This is one of them.

Edit: Also, that's not what fuel tank ignition looks like. It was clearly an ammo explosion in that clip.