https://www.sfopera.com/digital/ - San Francisco Opera usually livestreams the 3rd performance of each of their regular season operas for $28, currently. A ticket gets you the original livestream and a 48 hour On Demand link that begins 1 to several days after the livestream. The next opera to be performed is Puccini's La Boheme, on Tuesday June 10 at 7:30pm PT. The on demand period starts on Jun 16 at 10am PT and ends Jun 18 at 10am PT.
https://www.sfjazz.org/ - SF Jazz broadcasts a livestream concert every Friday at 7:30pm PT, and almost always make it available on demand in a week or so. Membership is $7.50/month or $75/year.
https://www.jazzlive.com/ - Jazz at The Lincoln Center broadcasts lots of concerts, usually as 2 separate sets, 7pm ET & 9pm ET; sometimes a single set at 8pm ET, occasionally even a matinee performance. Most are not made available On Demand, but they do have a lot of programs you can watch/listen to any time. Membership is $9.99/month or $99.99/year
Traditionally, Hardly Strictly Bluegrass & Stern Grove concerts in San Francisco were also available online, but it seems like there's less and less, and it's getting harder to find...
Please feel feel free to share any sites that you've been using for those nights when you can't get to a live concert!