I've been doing this long enough to never say definitively "It would never happen", but the clip does go a a little over the top. There are similarly plenty of instances of tanks actually getting so close to the enemy that they become intermingled, with the wrecks of both sides of the battle being right next to each other, so it stands to reason that the crews would similarly be in close proximity. See for example this image, the wreckage of two American M3 gun motor carriages (Tank destroyers) in between the wreckages of a German Panzer IV and Tiger. https://i.pinimg.com/originals/66/7e/cf/667ecfc8dd09ef7916bedd842edf93fe.jpg Survivors could well find themselves within ten meters of each other if the Americans had stayed with their vehicles for cover.

It starts out reasonably enough. There have certainly been instances where opposing sides seeking shelter from the maelstrom of battle suddenly find themselves sharing the same foxhole or building or whatever, leading to either an immediate truce between them or an immediate fight to the death. The scene in the movie sees the melee start after a group of Germans, on fire, head for water, only to discover Russians there too. However, the fight then devolves into other tankers coming -to- the fight.

Again, it's difficult to be definitive. The primary goal of an unhorsed tanker is to leave the battlefield and go find another tank, not to play infantry, a task for which he is ill-trained and ill-equipped. However, unit loyalty is also a thing, so if you see your colleagues or friends fighting for their lives in a melee, I could well see other tank crews finding this principle overruled and heading in to the fight.

So.. plausible, yes. Common, no.