That's because this ain't even roadrage (at least unless there's a version with audio that proves otherwise). I can tell what happened is this:

• The car on the left (the one who flips) was on a right-turn only lane.

• Because there's only one lane on the opposing side and they're a passive driver, the car on the right stops in the middle of the intersection.

• Car on the left owns up the mistake, signals the awkward driver to carry on with his hand (hence the waving motion).

• Car on the right understands, slowly moves forward.

• Car on the left tries to ease in on the pedal to slowly follow. Instead, he gives too much gas (or suddenly gains a lot of traction) and ends up driving into the other car, making tire-to-tire contact accelerating the entire car even more, and toppling over.