Hard to tell what he was "working" since he didn't narrate what he was doing. I think he executed everything pretty well, regardless. Looks like he had a decent landing option but I don't know if he was at best-glide since aerobatic biplanes (Pitts) don't exactly have a great glide ratio to begin with. It just seemed like he held an awfully steep decent initially (some of that was likely to regain speed from the 90-vertical he was in prior to engine stopping). I would have thought he would have tried to maintain altitude a bit more to buy more time to troubleshoot. Wonder if he ran out of fuel on that tank or if the header tank just went dry and he had to get more fuel pumped in before it would restart.
Edit: It was attributed to an older (less flexible) flop tube in the fuel tank. Here's a story on it, for those who care: