Kids today don’t know how easy they have it. Back in the day, I used to record and collect all the late-night music performances on videotape. I still have a giant plastic tub full of old Beta cassettes somewhere. These days, all you have to do is DVR everything — or watch the clips on YouTube. And if that still feels like too much work, don’t sweat it: I’ve got it covered. This week in late-night music begins with a nostalgic bang, courtesy of The Lemon Twigs, who brought their ’70s-style pop-rock to Jimmy Kimmel Live! Also on the roster: Meek Mill and Jeremih getting Dangerous on Fallon, folksinger Ruston Kelly doing a Faceplant (not literally) on Late Night With Seth Meyers and rootsy L.A. rockers Dorothy cranking out a suitably titled Flawless on Corden. Enjoy.