Over Christmas vacation my family watched a bunch of old home movies from when my brothers and I were little, around 1982 to '85. We made movies after that as well, but they must be under a pile somewhere. The last I remember was probably Christmas of 1990 or '91 being taped, and anything after that would have been very sporadic.
My mother has a DVD compilation of all of her old 8mm home movies from the '60s and early '70s. The same kind of events are shown there as on ours -- every birthday, every Christmas, and random special occasions. (My mother even taped my brothers "performing" in the daycare center's 2 year-old Olympics during the summer of '84. In hindsight, it's something we all felt like fast-forwarding through after a few minutes, but moms were more motherly back then and recorded more rather than less.)
Again that seemed to fade out during the '90s, and not just because we were too old to tape. My mother's home movies show her in high school, when her older brother had already become a father, etc.
By now it seems just about dead. My nephew is nearly 4 years old, and there isn't a single home movie of him, whether for a birthday, Christmas, or anything else. Sure, there are a handful of clips, but none is longer than about a minute, they are usually divorced from any context, and so there's no sense of recreating an experience. Also, we were with my cousin and his four kids (ages 6 to 16, I think) for Christmas, and there were no home movies being made. People still take pictures, but no movies.
The movies of me and my brothers go for about 10 minutes or more at a stretch, adding up to several hours per tape, and you get a good feel for what was going on, and how everyone was interacting with one another.
I tried to google around to see if there are any data to pin this feeling down, but I didn't find anything. Still, it was just so common to make home movies, and I haven't seen anything at all of my nephew. Some of my brother's friends have little kids too, and I think he would've mentioned it if they were very different in that respect. Like, "Yeah, they make lots of home movies of their kids, but as for us..."
Obviously it has nothing to do with economics, since camcorders only get cheaper over time, and we either stay the same or get richer. Not to mention easier to operate -- my dad had to hold that Betamovie camcorder with two hands and rest it on his shoulder, while wearing the giganto VCR itself (which held the blank tape) strapped over his shoulders, like a proton pack or something.
Technological change isn't it either, since people choose what to adopt, how often to use it, and in what ways. It's true that a smartphone is dumb as a camcorder, but nothing keeps people from still buying camcorders and using them the way they used to. "My iPhone wasn't built for that" is just a lame excuse.
Once again the changes seem to reflect the trend in the violence rate. Looking through YouTube for home movies from the '50s (i.e. before '59 or '58), they aren't as frequent as the ones from the '60s through the '80s. It's not just that the cameras weren't as common in the '50s vs. the '60s. They don't show very private or intimate events, whereas in the ones from the '60s the people are more open and not so concerned about being caught on film. Here's an example of Christmas from the mid-'60s. And then people in home movies only became less self-conscious through the '70s and '80s.
Nobody else was ever going to watch your home movies but you, so this isn't a difference between one time period being more private and another more exhibitionistic. It's more about how close you wanted to be to your family members. If you compare the '50s family sit-coms to the ones from the '80s, the family members are much more distant and neutral toward each other in the former, and more affectionate and looking out for one another in the latter. During the '90s and 2000s, they've returned to "it's nice that you're here, but I don't really need you."
Making home movies, then, was a way to preserve something that looked like it was being increasingly threatened. Not consciously, of course. You just care more about preserving something that feels transient, and take it for granted when it feels permanent.
That has lasting consequences, too. You can gather the family around and watch those old home movies as a rite of renewal for your togetherness. The Silent Generation never seemed to feel that way about their childhood as they aged, probably because they never got very close to each other in the first place. "Too mushy." I don't think most Millennials will either. Just as the Silent Generation mostly gets nostalgic about radio programs, the Millennials will get nostalgic mostly for TV and video games. Not so much the relationships they had.
This is further evidence not to believe the hype about the "family values revolution" since the mid-'90s. They're definitely hovering over their children all the time, but if parents so strongly value their family, then why aren't they making home movies like they used to?