hate to burst your bubble, but ...
I have heard of several variations on this method, although I will admit (by way of disclaimer) that I have never actually tried any of them.
Does this mean that I have serious misgivings about their adequacy and efficacy?
Yes, it does. Now, I am not a metallurgist, and I have no knowledge of chemistry except that you can only get so much salt into a glass of water, but I am by nature an empiricist, and if you don't show me something which will work, I probably won't try it.
Look carefully at the very last bit of the video: the lock functions normally when the fellow pulls the trigger, but
where are the sparks??
there ought to be enough sparks with a lock that size to start a bonfire, but I see nothing. Hence, the method does not work, except to burn up a good bit of otherwise perfectly good leather. If you have your heart set on doing this, I can't see the harm (except to the leather and the tin can), but I would most strongly recommend that you do this (a) outdoors and (b) upwind of anyone and anything you don't want to 'offend,' since most of us find the smell of burning leather off- putting.
This is most probably an India- made lock, which puts you in a good-news-bad-news situation. The good news being that you probably didn't pay a very great deal for it. (Of course, 'a good deal' is a pretty relative term, but I sincerely hope that you didn't plonk down a zillion pounds sterling for it). The bad news is that, as an India made lock, there is very little by way of standardization, and there is minimal quality control, so your lock might be made of good steel, or it might be 'mysterymetal' and you really have little way of knowing. I would hazard a guess that the frizzen is mysterymetal.
now: a note on the mechanics of the spark, and forgive ...
ff
ff
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the spark you see is actually a little shaving of steel which has been removed from the face of the frizzen. this tiny bit of steel has been shaved away from the frizzen by the sharp edge of the flint, and it glows white hot as a result of the friction which was generated as it was removed from the frizzen face. I don't know why, but this can be achieved by steel and not other metals, so if you don't have steel, you don't get sparks (at least, you don't get very many sparks on a reliable basis).
thus, if you don't have good steel in the frizzen, you don't get good sparks.
If for some reason you are not inclined to require the replacement of the lock in the entire, I think that there are two possible options. You may be able to re-harden the face of the frizzen with some stuff called Kasenite or somesuch ... there are several variations ... here's a link
https://www.youtube.com/watch?v=9tlsq2ESQz0
as you can see, the part you want to harden is heated, the magic glop is applied, the part is reheated, then quenched, and there you go... this looks good in theory, but as with the leather, I've never tried it. I cannot say how deep the hardening would go, or how long it would last on the surface of your frizzen, but the skeptic in me cries out that you'd be 'at it again' in fairly short order... again, I've never tried it myself and I may well be way off base. additionally, I have no idea what is in this stuff, or whether you are allowed to have it.
the other possibility to consider is getting yourself a bit of hacksaw blade or other similar material and grind it to the appropriate size, then heat and bend it so it forms the curve of the frizzen face. Silver solder this to the frizzen, and you might get better result than what you now see. since you now have the lock of frustration and failure, I see no loss if this doesn't work, but my first choice would be to demand a replacement.
now: a personal note:
many of us don't want to 'make a fuss' and I think that this is wrong: if you
don't make a fuss, if you
don't stick up for yourself and demand that whoever sold you this lock make it right, you are not only separated from your hard earned money, but you actually encourage the production of badly made goods by some arrogant fellow who has learned that people will accept whatever shoddy goods he cobbles together in some pest-hole of a sweat shop because they're 'too polite' to demand a refund...
OK- -that's my rant ... let me climb down off my soapbox before I fall and get hurt...
good luck with your project ... soon, I hope, you will make good smoke!