I only saw about 30 seconds of that video, but the maker was fascinated with the quality of the machining on the bottom of the frog. That's a waste of time. How much cast contact does someone think they're really putting a crushing force on with the frog screws? It could be a few nail heads and not have failure issues.
The real issues with most of those planes is that the adjusters are rubbish, and don't match with the cap iron, and the cap irons may not match with either the adjuster or the screw coming up through the plane.
On a perfectly machined frog, there are very few points of true contact. If we think that we have uniform contact on metallic surfaces with a couple of hundred pounds of force at the most, we're in the weeds.
I just tried to set up one of those planes or something similar - marked "buck brothers". It had terminal issues, but none were due to roughness other than the fact that the sole was hollow along the width (but absolutely flat front to back) about 5 thousandths. 5 thousandths is a huge amount. I filed it out and then finish lapped it only to find that the adjuster could not work in any way that the cap could be closer to the mouth than 3/16ths of an inch. The plane is rendered useless then because it cannot control tearout.
The adjuster was very light weight aluminum alloy or something and couldn't move the iron when the lever cap was tight, at least not well, and when the lever cap itself was tight, it was aluminum alloy and could not provide enough tension to the cap iron to keep the iron stable on the frog. All issues totally unrelated to cosmetics.
The cap iron was poorly made at the lip, but easily modified. The only thing useful on the plane was the blade, as any hardened blade can be made useful by accommodating it with sharpening (as in, if it's soft, don't put it in a guide and finish it through 30k shapton - give it a middle stone and buff it so that the weak apex doesn't remain).
In the end, after modifying the cap screw so that I could get the cap forward close enough to control tearout on the "buck brothers" version that looks like this plane, the adjuster was completely out of play and the lever cap was no good.
I that lever cap is heavier cast (even if it's zinc or something) than aluminum and has better stiffness, maybe it will be OK.
Sole has to be flat, everything has to screw tight, iron needs to be sharp and mated to the cap, and the cap has to be able to get to the tip of the iron without being out of the adjuster range - those are the key things for a bailey style plane.
(i've had some old ones that had twist or a lot of wear, too, but the last two new planes I did had more overall flatness issues - both hollow one way or another. bad enough that they wouldn't have worked well as smoothers. The stanley mexico with plastic handles was *miles* ahead of the buck brothers, and is entirely usable once fixed - but could still be a risk. The last late sheffield plastic handle stanley that I got also had a problem with the adjuster (it was 1 1/2 times as thick as the slot in the cap iron and the cap slot had to be filed open just for the iron to be able to get down to the frog. It teetered at least 3/32nds off of the frog as it came from the factory).
I'd rather have a later model vintage plane at cost neutral - I always like to think I can fix anything, but some of these off brand bailey pattern planes have issues that would really require things like making an entire cap iron and completely replacing the lever cap. The stability issue I mentioned above was gone by using a stanley lever cap instead of the aluminum one that came with the plane. If someone tried to file the frog or whatever to fix it, they'd see no improvement.
