I guess, the point is that when you sit near the wall, it will look like the wave is travelling the angled wall super fast to then transfer to the perpendicular wall and move normally.

I guess, that constant shaking and splashing was chosen for a demonstration exactly because it obscures the fact that travel speeds aren't consistent

The fact that all the video is from 1 angle is the biggest giveaway.
If it was good inside the box, there would be loads of footage from there. That would be a very unique experience, because all of these things are forced perspective. It's just the way a 3d scene being rendered onto 2d surface viewed in a 3d world works.

The water is probably abstract enough that it's not as noticeable, but I bet it looks weird AF (and not in a good way) when you are sitting in there