86
he entered the initial turn, banking to about 45 degrees with an appropriate airspeed
however, i think, the aircraft was travelling below the stall speed for a 60 AOB, therefore causing the wing to stall
Sorry my friend but there is no such thing as a simple stall speed/AOB relationship. For example you only stall at 1.414 times the wings level stall speed at 60 AOB IF you pull the stick back and try to hold height (ie actually pull the required g such that the vertical component of the lift vector equals the weight).
You can take an aeroplane to any bank angle you want but it NEED not stall. It will only stall if you reach the stalling AOA.
Good luck with what you are trying to do but my personal view is that the video by itself is not enough to establish everything that was going on aerodynamically.
If I was your tutor and you explained why you could not provide a definitive answer I would give you A+. He/she may sneakily be trying to make sure you understand that the much talked about 'stalling speed' is very often meaningless. Stalling is about AOA and little else. (I say little rather than nothing because under high IMN conditions the stalling angle of attack of a wing will reduce slightly)
JF