By no means a expert, but I do know what I see and things to look for - that Hurri was indeed slow over the top no doubt about it. The last beat up was noticeably slower than the initial beat up as well, so he was slower over the top of that wing over than perhaps he would have liked. I suggest he pulled a little too hard to get around the corner for correct line up with the runway and dynamically stalled one wing causing the roll. There could have been a element of torque rolling with the prop (Merlin is clockwise when viewing from the cockpit I understand) at that low speed too making matters even worse. Anyone who has dynamically stalled a aeroplane gets this. Against the prop the flick is small, with the prop and the flick is much larger.
In my humble amateur opinion this is too low a airspeed with a hick up at too low a height to recover. Another 20+ kts on the clock and 200 ft over the top and this crash would not have happened. Why the pilot was slow in the pull up is anyone's guess - not enough fast lever forward (boost), who knows. Easy to critique post tragedy, but there it is. My condolences pour out to the pilot's family and friends.