It looks like maybe my ISP is forging their Ookla speed test results. Whenever I use that speed test, I get the speed I paid for, but performance otherwise still seems slow. Whenever I use other speed tests, I get results that are a quarter to a twentieth as fast.
The tests were not concurrently run. They were sequentially back and forth several times for consistent results. I’d need a lot more data to say one way or the other. I have not gotten to the point of running a thousand automated tests on every tester I can find.
Both consistently slow or intermittently slow Internet speeds might explain the issues streaming Hulu and Netflix. If it was intermittent, then in testing the speed the service might decide high speed means give me HD quality, but then a slow down causes it to start buffering and before it downgrades the fast speed is back.