It’s more a function of having solid catch and engaging the biceps, triceps, lats, pecs, etc. it isn’t evident that there is much of that solid pull from the quick video.

Technique may look fine but you can tell the difference between a 1:00 swimmer and a 1:40 swimmer pretty easily even when in different pools.

Don't disagree there, but if I intentionally slow my swim pace to 2:00, it looks like I'm joe average BOP swimmer, whereas once I take it up to race pace 1:30, I obviously look a lot more competent, and moreso, a lot more powerful a swimmer catchwise and turnoverwise compared to 2:00/100

That's not at all a function of techical breakdown in my case - that's a matter of having enough oomph in your muscles to execute that powerful catch over and over again at pace. That 1:00 swimmer would still be a powerful swimmer even if you made him swim one-armed, pop his head out of the water on every breath, and forced him to do a big dropped-elbow catch literally that looks like a one-armed doggie paddle. He'd certainly swim faster than 1:40/100, and that's remotely because of his awesome one-armed techinque. (I have tested this very dropped-arm one-arm head poop thing, and I go from 1:30 to 1:50 which is still triathlon MOP. I don't all of a sudden go to 2:10 BOP pace even with that hellaciously bad form.)

OP is even better off in that his stroke looks really clean and smooth, so it's almost entirely a power issue, not some catch form deficit - although I'm sure it's equally valid to argue that the power really just allows him to hold correct form at much faster paces so it's related (I will still call that predominantly a power issue, as opposed to a BOP swimmer who has a big x-over and huge overroll which are predominantly technical errors that power improvement will not fix)

Looking at your videos I think you've made some great improvement, so don't short-change yourself. When I started out I wasn't that much different than you are now. There's nothing I can add that the experts here haven't said about legs, back, shoulders, engaging your core, evf, etc. But how about upping it to 4 swims/week. Ken said a long time back (and its so true) that you get instant feedback with every stroke, so the more you swim, the more feedback you'll get. That's held so true with me, and I've tested so many alterations until I think I found one that works for me. Also, like another poster said, its probably a little strange (or more difficult) to pick up swimming as an AOS rather than having it ingrained in you as a kid, but its not impossible. I suspect you'll get there soon with more days of swimming.

If you want to look at some YouTube videos, my favorite videos are from David Marsh and Mike Bottom.

I read up a bit on TI and chatted to a few people about it. There is some useful stuff, but I kind of switched off from it as I was reading too much contradictory stuff or stuff that just didn't seem to make sense, at least not when you consider racing. But yeah body position is so important. How many average swimmers have poor body position - 90% probably? One guy in the slow, slow lane in my masters squad, his feet almost touch the floor in the shallow end when he's swimming freestyle!

 May I suggest using a snorkel and a pull buoy. Keep the buoy at your ankles. Go 4x200 with 30 secs rest. Do this every workout.

You will engage your core, lengthen your stroke and you will naturally fix a dropped elbow or cross over in your stroke.