Agreed, if you wait, you'll often get a few seconds of usability, and things that you had tried to do suddenly get done, but I've found that it doesn't last long. What's especially interesting is that even if you succeed in quitting Safari (or whatever browser you were using to view video when it happened), it doesn't clear the problem (there are various other processes still laying around). Nothing short of a reboot seems to work (except, as I mentioned, managing to find exactly the right process(es) to kill).
Anyway, sure, whatever's going on will eventually allow someone to get to the root cause of it. You have to believe that people at Apple have hit this and that it's as annoying for them as it is for everyone else. Having worked at more than one high-tech company similar to Apple, I can tell you that engineers don't ignore this sort of thing when they hit it. The fact that it's not solved by now leads me to think that (1) it's really hard and they haven't managed to find it or find a fix (frankly, I doubt that's the case), or (2) they know what it is, and it's a hardware bug or something similarly ugly that can only be fixed in future mac products and they don't want to reveal that, as it would be a marketing nightmare and could expose them to lawsuits (you wouldn't believe how often that consideration enters into decisions that you'd think would be purely technical). Didn't somebody at an Apple store suggest "buy a new mac and the problem may go away"? Hey, that was the recommendation I got for a problem with "Other" sucking up memory space on iOS devices (discussed at length elsewhere on these forums and still not fixed after all these years): buy a new one with more memory!
You might recall that there was some discussion way up at the front of this thread about a possible graphics chip failure. That was pure speculation, as far as I can tell, but it may have been uncomfortably close to the truth, if such is known (and I really think that it is - when we were debugging tough stuff like this, we never failed to nail it given enough time and info, and I'm sure that Apple's engineers are every bit as good as my teams were).
So hoping that somebody else has the patience and time to waste .. er, devote .. to killing processes and taking good notes (unlike me - hey, I'm retired, I don't do this for a living anymore).
Not to be too cruel, but how can you live in a house that doesn't have at least two or three computers? I didn't think that was even legal anymore ;-). Seriously, though, you can ssh in from an iOS or Android device with the appropriate app and everyone's got a bunch of those. If you want to fool around with it, I'll give more details. It's not too hard and you can't do too much damage to your mac ("too much" is key, because if you're lucky, you can definitely do some permanent damage fooling with sudo).
I had another thought before I sign off: if people would like to note what kind of CPU and graphic chips their Mac has, we could probably spot some patterns. For the record, my MBP has a 3GHz Core i7 processor and Intel Iris graphics with 1536MB memory. As I said, I suspect it has something to do with graphics hardware (based on nothing but observing symptoms and reading comments in this thread).