Nice to see no injuries.
What I see in this video is the mustang is no longer maintaining his turn.
He should be far above the skyraider and much further into his 180 degree break turn.
He's still banked but he's no longer turning before the collision as all the other planes did from the previous passes.
He was banked but no longer turning or climbing.
I'm wondering if he experienced a failure before the collision.
I agree the skyraider should have maintained separation but I'm not sure how much he could have done when faced with a plane that seems to have slowed greatly, stopped turning, and descended.
YouTube - ‪Duxford 2011 P51 Skyraider Crash‬‏
IcePaq, if you look at the footage just as they break you can see in the distance that no 4 from the previous break is only just on a very early downwind (and right up his No3's chuff), if the P51 lead had not shallowed up his turn I suspect he would have had issues running into someone on the downwind.....