They all looked high
I've been squatting for about six months; for the last month I've had knee pain that got bad enough that I took a break for two weeks. It matches up with descriptions I've read of PFPS / runner's knee (and when I've run regularly in the past, I've had similar pain develop). Tried TUBOW for the first time yesterday, not sure I'm quite using it right; form check on that here: TUBOW Squat Form Check - YouTube. I also did a set without the TUBOW; form check on that here: 107.5kg x 5 Squat Form Check - YouTube (I know I went shallow on the first rep; are the others too deep?). Apologies for side angle rather than 45 degrees, will get other angles next time. Thanks for your help.
They all looked high
Where is the TUBOW in relation to your foot? Is it in contact with your shoe? This is a bad angle from which to film a form check. It's hard to tell from here, but your stance may be a bit narrow. I also suspect that your knees are not shoved out sufficiently, and that you're not clear on the concept of hip drive. And as Ryan mentioned, you were nowhere close to depth in the TUBOW-free set.
Thanks for the feedback, Adam and Ryan - really helpful. TUBOW was in line with my toes, about an inch in front of them. I'll post a video from a better angle when I get a chance (probably not for a few weeks - moving next week from South Africa back to the U.S.).