Ask for a still and there is exactly one thing to get right. Ask for a clip and every frame has to be a plausible successor to the one before the same object, in the same light, made of the same stuff, having moved a believable amount. That constraint is called temporal coherence, and holding it is the entire difficulty of the medium.
A video model is not an image model run many times. If it were, you would get ninety unrelated pictures of roughly the same idea.
It also explains why the difficulty is not evenly spread. Early frames have almost no history to contradict, so they tend to look excellent. The further in you go, the more there is to stay consistent with, and small deviations compound rather than cancel out.
Which is why the honest framing is not “how good is it” but how long can it keep this up and that is a question about the clip you asked for, not about the model in the abstract. A static scene with a slow push-in can hold for longer than a person turning around, because far less has to stay true.