I thought about that too but came up with a workaround: it suddenly appears at that point in the cloud, displacing the puff seen. The puff actually is symmetric about insertion point, but due to the asymmetry of the cloud and the camera angle it appears like that.

Not more of a reach than many debunking chain-of-reasoning explanations, with the exception of the how.

I thought about the second point too, I don't think you need exact synchronization. You just need many more "stutter points" than framerate, and the camera will capture some of them. A way to check that would be to see a longer distance video, and observe other "cloud puffs" without seeing the craft there: you just see the trace of it.