As you got in touch about this - I thought I'd reply here, just to continue this thread, rather than just an off-shoot. (Hey Mr Plumb!)
I think the flaws in the 10spm have been covered well by Spider and Plummy. You look very tense and mechanical - remember, the sequencing is meant to flow from stage to stage, rather than 'clunk' (clunk is the wrong word, but I've just sat here for 2 minutes staring out the window, trying to think of a better word - and failed).
Spider's suggestion of slight circles with the handle could help here. I'm not an advocate of the "Scraping the handle across your legs" technique - as I feel that has the potential to totally destroy posture. However - in both videos, you are VERY tense through the shoulders. Shrugging them even - and that's one of the two big things I'd try to work on if I were you. By the time you come into the catch, your shoulders are almost up at your ears.
So as you finish, I want you to think about passing the handle underneath a table. Not a thick table. Just your ordinary 1 inch thickness. So come to a finish - then pass the handle under the table, and then as you come into the catch, raise the handle to get back up over the top of the table.
WARNING - when you lift at the front - do everything you can do not open your hips up at the same time. This is why I just want a small drop. And this danger is why I don't like thr "Scrape across your legs" technique. As it leads not only to a slumped posture forwards, but a really early opening of the hips at the front.
Take it slowly, no actual rowing - and get used to this. Small circles, under and over the table. Hopefully that'll help lower your shoulders a bit.
You're doing what I do....
On the recovery, you get your hands away, body rocks forwards (let's not quiblle abou the knee bend being a bit early) and then as you get to the front of the machine - you add in an extra forward lean, which takes you plunging down to the front. This over-extension then weakens that 'bracing power' you'd have with a more powerful posture. And it's likely the cause of why you open your hips early - and it's almost certainly why you are grabbing with your arms early too - to overcome that forward lean. Although we're discounting the 20spm row - because of the speed you're rowing at, it's a lot easier to see this happening at 20 vs 32, but the overlean is still there - you can see the rounding of your back as you try to squeeze out more length with that extra bit.
So ironically, what I'm saying here is that I want you to lean LESS forwards at the front - but then hold that angle as you drive back.
I do wonder whether addressing your shrugged shoulders would be part of solving this too. Like I said - if you look at the catch position on the 32 - your shoulders are up at your ears. So if you can acheive a less rounded, more powerful posture at the front, alongside less shruggy shoulders, the two elements should fix themselves!
Spider's comment about raising the footstretcher is interesting. Personally, I wouldn't. Your shins are at vertical, and there's still some compression available as it is. If you lift the footretcher, you're going to put an awful lot of pressure through your lower back to get to the same compression.
If you're going to try socks - try it without moving the footplate, and then again with raising it a notch (to compensate for no heel in the shoes) and see how it feels. You look so 'bound up' at the front, that if you can find a way to be more powerful to hit that opening power in a stronger way - that would maybe help.
As always with technique, it's easy to pounce on these things. But it would be remiss to not say how good your stroke is in general. Nice timing, looks like you're getting power in from the legs and arms well - just a few tweaks maybe in order to get that power through effortlessly.