I spent about half an hour (maybe more) on the phone with my DSL provider, and I'm getting the range that I'm paying for, though various online speed tests give wildly fluctuating numbers. At any rate, I was very impressed with the time they took and the attempts they made to see if there was any problem on their end.
I got a suggestion on an Adobe forum to download and run a "deep clean" program. I may try that before too long.
At any rate, probably about all I can do is accept the fact that now for whatever reason, flash videos don't play as well as they used to and live feeds don't play at all. Who knows? It may be that if I just forget about it for a month or so that one day I'll go back on and it'll work fine again.
Thanks again, fellow FReepers!