I wrote a long reply but basically my conclusion can be summarised as...

* Forget what you look like, the only objective measurement that matters is the wall clock.
* Symmetry in your stroke has no relation to speed.
* A scrappy looking swimmer can be a fast efficient swimmer.
* 'Feel for the water' is a myth so find a stroke that works without finesse.

With that in mind is video analysis always that helpful?

Swimming isn't a scientific paper. It doesn't have to survive the process of peer review. You just have to beat them in the water.