One of the nice things about streaming services like Roku is that browsing is like shopping but for stuff you’ve already paid for. Though it’s not new, I recently came across the Alabama Public Television show “We Have Signal,” which offers a couple-dozen musical performances filmed at Birmingham’s now-closed BottleTree Cafe. Though it’s bad that I’m so behind the times, it’s also good . . . in that now I get to watch all these shows that are new to me.