I can't speak for Nutty, but in my case nothing in my setup has changed, and, as I said, midis on all other sites continue to behave normally. For some reason, Netscape's native plugin no longer recognises midis here as files which it can open; if I save them to disk, however, I can open them with that plugin if I particularly feel like it.

One particularly puzzling thing is that I made quite a lot of the midis on the Mudcat Midi Pages myself. I certainly didn't use up-to-date software! I can't play them from there any more; but in quite a few cases there are links in old threads to copies of the same midis at the South Riding Folk Network site (I used to put them there in the days when the midi pages here were not being maintained) and they play perfectly happily through those links.

I can only guess that the Upgrade is responsible, but I can't think how. Altogether rather baffling.