I’m going to say pretty much what @dverhey said. Personally, I love stand up comedy, and I have never once in my life seen a live comedy show on TV that had commercials. The only network I know of that ever broadcasts live comedy is HBO…generally I think it’s deemed too risky for commercial television with the possibility that they might go blue. Most comedy performances are filmed live…the comedy show was recorded live, but it’s edited for broadcast and what you normally see is they will pick a point in the show where the comedian has paused for laughter, or when he switches topics for them to interrupt for the commercial break. Comedy being all about timing and pacing, it would be impractical to show a live comedy show with commercial interruptions. If a network WERE ever to try doing that, I’d suspect they’d probably break away and come back and let the comedian keep his routine, because if you break pace in a comedy routine, it’s not going to be very good.
The only exception I can think of, and I actually DO have an answer for this is TV talk shows, like the Tonight Show or the Late Show or what not, where you have the host doing a monologue and then they go to commercial and the host is now at the desk and every commercial break inbetween the host stays at the desk, you kind of wonder what they do, or what the audience does, and that I can answer having been at a taping of one of these shows many years ago. Essentially the band plays and the host either just listens to the band, grabs a few sips of water, and maybe chats a little with one of the guests if the guest sticks around during the break. Before the show they bring out a comedian to warm up the crowd, and they go through the “rules” like pointing out the applause sign if there is one, maybe they ask the crowd a few questions so that if someone has an interesting story they can give the host a note. Towards the end of the show they might have the host do a couple of voice promos for the local affiliate.
But most live comedy shows the comedian comes on, talks for 45 to 75 minutes and leaves…rarely is there an encore, rarely is there any break in the action, and if you want to show it on TV, you film the whole thing and break it up and insert commercials in the studio.