That TB20 gear up landing has been around the net for a little while.
I am not sure if it is relevant to the Mooney video, because a TB20 has squat switches (they cost £1200 each
). It also has two interlocks, either of which gives a warning horn. One is gear up but landing flap selected, and the other is gear up and throttle below a certain position.
Some pilots who are used to big runways land the TB20/21 with
takeoff flap and that disables the first gear warning, and then you are left with only one gear warning which is the throttle lever position and that one is fairly easily defeated by landing into a strong headwind.
There is no reason, ever, to land a TB20 with just the takeoff flap.
As a result of the two interlocks, plus the usually fairly obvious difficulty of getting the thing to descend fast enough with the gear up, landing gear up is very difficult in the TB20.
To me, that video is a bit of a mystery, unless the pilot(s) was/were very new on the type and perhaps had no training on the system, which is possible.