Do you know how the single that was drafting managed to remain behind the tandem after it started to quickly slow down?
The following rider was Craig MacLean. Craig is a former silver medallist in the world sprint championships, he's very experienced and can really handle a track bike....I've not discussed this incident with Craig but it looks from the video as if Craig had already backed off (perhaps at the start of the back straight) before the accident happened as he wasn't visible in the shots of the tandem going along the back straight. He reappears near the end of the clip by which time he's already at the top of the track and clearly travelling at well below sprinting speed.
I also know (from painful experience) that, when your wheel collapses on a track tandem, you don't spend that much effort trying to kick back to slow it down. All your concentration goes on trying to keep the damn thing straight and upright! (My wheel disaster was a rear hub snapping in half when we jumped. But it was on a big outdoor track and a rear wheel is easier to deal with, Barney did incredibly well to hold a front wheel failure on a steep 250m track.)