Also anything you generally find relaxing that isn’t intended to be.
For reasons I cannot articulate, I never liked intentional ASMR videos, but give me an upload of a three hour video course about a word processor from the 80s or a training video about how to take a sonogram of the kidneys and I’m all in.
As for generally relaxing stuff, for some reason I find recordings of radio comms, like storm spotter nets, to be relaxing. Also local news coverage about major weather events.
And to you UK lemmings I know about the shipping forecast.
I have a fascinating ASMR-like sensation that comes from listening to other people get massages. My gf uses this neck/back massager and the quiet droning, like a cat purring, just sends my brain to the other dimension.
But for online stuff, unironically, the first part of massage porn videos.