That tank is WAY too small for either of them - even though he calls it a "nice big tank". And the instant he says he's going to stunt the growth I lost all care for this guy as a keeper. The damage done with growth stunting is very well documented. "If your shark gets too big, let it go" - wow, one of the WORST things you can do. So sad to think someone like this is thinking he's doing the right thing. Black tips, not well, and not for long. Bulls? Not a chance.
Blacking out windows, bubbles walls etc... are all old tricks. Corners aren't issues. The length of the glide path is. Most ORV sharks can handle corners just fine. You need to consider the corners unusable space when looking at where the sharks can swim. The sharks will have to make several quick/jerking kicks to make those corners. This is bad for the sharks to do repeatedly over a long period of time. If you want a display/tank with corners, you need to draw a circle on the inside to depict the actual glide path for the sharks you plan on keeping.