I'm intentionally ignoring the improper finning, silting, lack of redundant air sources, standards violations and other foolishness to focus on other clues here.
Top to bottom, left to right:
0 seconds: No tank valve band, and her tank is far too low. The tank band is installed backwards and isn't closed.
2 seconds: Our instructor has loose tank bands (probably because it's a BC that's been overused and uncared for).
4 seconds: Dangling equipment.
40 seconds: Tank placement again
1 minute and 47 seconds(below): Standing on the deck.
An instructor or divemaster that doesn't take the time to ensure his own gear is serviceable and who sets a bad example is setting students up for failure.
As a diver of any level, you should be looking for the little things that will help clue you into who you are diving with. Divers who doen't know (or have forgotten) how to set up their gear correctly are signaling that they are going to problem prone in the water.
Imagine this dive if any one of the them had to buddy breathe and exit that wreck. It would likely have been a completely different dive.