Thanks for the thoughts. Some questions: you both say "vertical" and if understand you correctly, you both imply that I should be planting my paddle vertically (as seen from the side, I presume). I was intentionally not planting it vertically, with he idea that by the time I get it fully underwater it would be about vertical and I would then unwind and pull. Another reason for not planting it fully vertically is that I'm under the impression that if there is a slight angle, I could benefit from the lift generated when the paddle enters the water, before it is fully submerged. I've read anout this and I think it works. This is different from pulling back before the paddle is fully submerged (which would result in lots of splashing and turbulence).
I did work on taking the paddle out of the water more through the rotation and less with my lower arms. I think thick as helpful. I also worke on taking the paddle a bit sooner out of the water so that I did not pull to the rear past where it is useful.
Next I worked on keeping my torso rotated during the catch (is seem to be unwinding a bit too early in this video here). This seems to help too, but is not easy, especially when it gets a bit bumpier. Lifting the pushing arm's elbow a bit up seems to help with this a it lines-up my joints better for the pushing arm in the catch phase and the power phase.
Lastly, I lengthened my paddle a bit. It seems to allow me to do a better catch.
Oh,and pausing for the prep time - I do they to slow down sometimes, but I don't want to do it artificially - I try to be more fluid from stroke to stroke, though I guess a bit of a pause will not hurt to practice while I try to get things under control
I'll shoot another video shortly and wanted to work on some of these points a bit before I check progress. But, if you have other comments in the mean time, please share.