You're watching the 1985 1000 km of Spa, riding onboard the #2 Porsche 962 of Jochen Mass and Jacky Ickx as it dices with the #19 Porsche 956 of Thierry Boutsen and Stefan Bellof. One of those drivers would not survive the race.
This is ten minutes of the #2 car's onboard, covering the start and some of the middle of the World Sports Car Championship race. The cars are brutally fast and notoriously challenging to drive. These Porsches, for instance, get all their speed from ground effect downforce. The thing is, for the ground effects to work, the car has to be stable and low to the ground. Bumps in the road don't just upset the suspension, they upset the ground effects and the downforce. Spa was a bit bumpy back then.
What this onboard does not show is what happened on lap 78 of the race. The young Stefan Bellof, a rising star in F1 as well as endurance racing, tried to pass Ickx through Eau Rouge, struck the older driver's leading car, then collided with the track barriers. Bellof did not leave the track alive.
That entire fatal wreck was caught on Ickx's onboard camera, the same one that recorded the ten minutes of video above. You can watch the awful wreck here, though it's not easy viewing.