Just to clarify, this video of F-35B is of its slowest landing to-date. 40kts I believe, and one of the last 'gates' it makes before shortly doing its first hover. So, any talk of "high AoA in the hover" does not apply here.
The high apparent AoA is controlled/optimised to maximise the wing lift generated, offsetting the amount of delta needed to keep it up by the engine (engine life etc) and this is part of the design for slow speed flight. During the later part of the video showing the aircraft from the rear, I would imagine that G.T was looking at small directional inputs (bank controls 'line' blah, blah) at that speed as part of the test.
Great achievement in aviation by any standard, regardless of those who pooh-pooh STOVL F-35 as a required concept.