Are the artists actually playing the instruments? Much of the time, yes. Are we, the listeners, really hearing that playing? A great deal of the time, no.

Many artists play (and sing) over the studio track, but their instruments aren't routed to the main audio outs. I have seen some performances where certain instruments, such as keyboards, aren't even physically plugged in and turned on.

On a related note, in some cases, the song an artist is performing doesn't feature certain acoustic instruments, yet the TV lives will include a band with those instruments. Take a selection of Ayu's past TV lives, for example. Some of the songs featured programmed drums, but a live drummer (who we couldn't hear) played along on TV.