I believe 'yes' and 'no', at least as far as Later ..., if that's what you mean, is concerned. The artists do indeed play live in front of the audience. But the whole show is recorded ahead of transmission. I saw KT Tunstall talking about her (now famous) first appearance and she said that she'd basically have got just a couple of chances to perform what was quite a tricky sequencing number. In the event I think she nailed it first time. But the subsequent editing wasn't very sympathetic.