I don't have any idea how those cars operate or behave and am dead certain that anyone here who pretends to is talking out of their asses.
I have no idea what happened in that video aside from it just being horrific.
As a formerly obessesive motorsport fan I know enough to see that the stage has been set for a tragedy like this for quite some time.
Sprint Cars are the most dangerous race cars. The issues with the frames are not relevant but the issue of visibility is.
It's night time. Even with the best lights visibility is less perfect than in any vehicle. The victim is wearing black.
Sprint Cars have those big tube frame bars on the left and right side of where a windshield would normally be. Horizontal view is limited.
It's a dirt track. Clods of dirt collect on the helmet visor. Drivers use tear offs (multiple clear plastic "stickers" that are layered on top of eachother) protecbut they usually wait for the visor to get "full" before sripping it off for a fresh one.
The victim likely saw Stewart's car and moved closer to him. This always happens.
Nobody can drive a Sprint Car better than Tony Stewart. The idea that he lost control of the car under caution, is possible but not likely.
Either way, the conditions were set for a pretty bad accident and that is what happened.