Tim Your memories of the videos were better than mine, and a re-watch of the ones I'm thinking of confirm that you are correct.
It is indeed up in the air, upon closer viewing, as to whether they're supposed to be the same characters. I sort of assumed they were based on similar production value, actresses looking the same, and how closely it dovetails together. The belt looks like it's largely the same with a different external lock.
The flashback-fantasy video ends with her belting herself in the present but no clarity on what happens next. My read on this was that she discovered an old chastity belt in storage, and then fantasized about the fate of previous generations locked up with no hope of escape, and imagining what it would be like for her to experience. Hence the spanking and being locked in the closet alone to examine the belt. In the end she belts herself and we see no more. My memory filled in the image of her being caught in her own locked belt, and being required to wear it permanently as punishment. (Any woman who places a belt on herself, by this logic, is one who needs to be kept in it. Volunteering out of curiosity tends to have long-term consequences.) I think I mixed up the ending scene with the scene of the older woman catching her and getting her in trouble.
That said? I feel like the story continuity holds up -- the flashback taking place before the wedding, and her being permanently belted as a result. (One might even speculate that the "vintage" chastity belt used the wire lock and then the mother applied a modern padlock for added security.) It might even be that the woman locked herself in, found that she could not remove it, asked the mother for help, and was told that she had to stay belted.
Time passes, and the marriage arrives, and she desperately wishes that her husband will not learn the secret of the belt, hence her pleas to her mother on the wedding day. With this additional context, I believe the husband never knew about the belt, hence they never discussed it beforehand, and she had simply hoped he'd never know. But the mother hands off the letter and the key, and I strongly suspect she is leaving up to his authority as to whether or not his new bride will be kept secure afterwards.
The man does not strike me as responsible, but he also seems to have a certain insecurity that would cause him to find the belt an attractive prospect. She's already playing the role of a submissive, housekeeper wife -- note how much she tends to his needs even those SHE is the one trapped in a belt. I do not have high hopes for her future freedom or release from the belt. If he asks her to go back into the belt willingly, for the rest of her life, I suspect she will obey.
Also, I'm 100 percent sure the scriptwriter likes tears -- that's a common thing in this kind of field.
The slice-of-life thing is entirely accurate. I feel like this could have actually happened to any number of people on this forum.