I wondered about that getting ahead to video it at different places, too. Then I dismissed it because of many possible explanations including even a road which paralled the general direction of the stream or maybe multiple camera operators pre-positioned along a known flash flood path. So I let t go.
I also wondered about undercutting of his position in one sequence. That's what causes the meandering of streams. The slightest difference on one side versus the other and the erosion is greater on that one side. Once a curve due to this starts, it gets "worse" and "worse" resulting in the stream going this way and that way and this way and that way throughout its course.
Viz.
More (You can see several examples of islands being formed in some of these):
https://duckduckgo.com/?q=meandering+river&t=brave&iar=images&iax=images&ia=imagesTerry, 230RN
Pic credits in properties