I've seen this clip trotted around as an example of how a Bjj exponent would fight in a given situation, and it's nonsense. A better example would be how the Gracies or Pedro Sauer fight. In those examples, the Bjj exponent is striking to set up a clinch and then a takedown. The ending position is almost always either in mounted, or rear mounted position, setting up ground and pound, or the RNC. Occasionally you'll see Guard, but that's usually when they fight against experienced grapplers, and need to tire them out.
I find it bizarre that you've seen the inverted Guard a "few times" in a SD situation when its pretty rare even in competition where the rules protect you from getting jacked up in that position. You don't even see it in the UFC, because the guy doing it like that would get punted like a football.
I think it's more from failures to apply a technique or the result of attempts to pull down, or strike to the head sending them down, I see my kids do this all the time. I've seen scraps like this very often in pubs, pool halls outside nightclubs at night etc. Commonly fueled by alcohol, but not always.