No, that's not a real person flying out of this rocket sled flying down the track at 600 mph. It's a mannequin test of a new ejection seat system for the F-35 Lightning II fighter jet. From BAE Systems:
The system has been tested to its limits, as a full scale front section of the aircraft, complete with ejection seat and mannequin was launched at speeds in excess of 600 mph down a test track. More than 30 ejection seat tests have been completed in the UK, France and the USA."British Team Completes 600mph Ejection Tests for F-35 Aircraft"
Witnessing the final test which took place at Martin Baker’s facility at Chalgrove Airfield in Oxfordshire, BAE Systems’ Test Manager Rick Whittaker commented “Ejecting from an aircraft like F-35 typically takes no more than three seconds from the time the ejection handle is pulled to the pilot being on a parachute. You can imagine how quickly everything happens. Incredibly, during the tests up to 900,000 measurements were recorded every second and I am pleased to say the systems performed really well.”