It does say in the video that the instructor let her get low as part of a demo as she had been flying low approaches and dragging it in. I don't know if they saw the Dash and/or were warned of wake by ATC, if they were then I would say this was foolish on the instructors part. Either way it nearly ended badly and it reminds me of a recent crash in the UK in which an instructor allowed a student to get low on final to demo something whenever the donk stopped and they had to find a space for it in town short of the runway.