Yeah, I'm not sure what it's evidence of.  We do know that there are some very fast jet streams circling around what would be the edge on a flat earth.  I'm not sure that I buy the explanation that this is due to lack of land around Antarctica.  To me, it would make more sense that you get those streams due to the firmament around the edges, but who knows?  In that video, there were lots of "scientists don't understand why ..." to suggest that nobody really knows.