So not only did the Youtube team look, they listened; they responded; they fixed. Quickly.
Frankly, I'm very impressed with the way this played out. I was expecting to view tiny little Youtubes for some time, if not forever more. Instead, this bug was squashed in a day. Wow. (I found and reported a bug in One Note years ago and still get responses/ reminders from the MSoft support forums about the unresolved issue. I think Redmond is a big, scary anechoic chamber, but that's another topic.)
It's great to see the big guys are, at least occasionally, still listening to mere mortals!
Perhaps it's time for a new MacBook Air.......