I know this is an old thread - but hopefully my .02 will help someone. If you see a "live" concert on the telly, or even if you're watching it live at the event on the bigscreens, there is a very good chance the video will not be totally synched with the audio, which makes it appear like things are being lip-synched or tracked/looped or whatever. While that stuff could be happening, the out-of-sync audio-video is not a good way to tell. Anything being recorded for distribution later will be recorded to a master "clock" - that way all camera locations will sync with the audio track - however real-world delays between where the sound originates and where it is recorded can be long enough to make it look out-of-whack. Similarly - front-of-house sound engineers in a huge venue will put delay on the main speakers so that the sound coming from the stage will be in sync with the PA system. This can be as much as 15-20 milliseconds, which doesn't sound like much, but it's enough to make singers look like they'e lip-syncing and musicians look like they're playing along with a track and not generating the noise themselves. In theory - if all you wanted was close-shots of the performers and sound from the stage only - there would be no problem -- but video producers often take their chances and sync the audio tracks (which are recorded directly from the front-of-house feeds) with pictures of the big-screens (delayed) mixed with close-up shots of the artists (not delayed). This again will make things look slightly out-of-sync. So they have to pick and choose the worst of the evils and go with it. Some shots will look good , others will look out-of-whack, etc. And yeah - the onstage "bell" in Viva La Vida most likely is triggering a bell sample - trying to mic a real bell, keep a real bell in-tune, etc etc would be a nightmare. Using it as a trigger for a sound they can control is a much better solution - i'ts going to sound great every night. That's it - thanks for listening to me.