Lip Synching and its importance

When I come to create my own music video I will need to have my actor/singer lip sync the words to the song I chose as well as sync any instrumental moments on a guitar or drums, e.c.t. This is so when the audio is added it is in times with the moment of the lips or any instrument played in shot so that it matches up otherwise it looks really off and takes away from the rest of the  video.

 

A good example of this is Coldplay - The Scientist because not only does the audio match up with his lips because the entire video was filmed and then played in rewind he had to learn to sing the entire song backwards so that his lips would matchup with what he was singing in the video.

Instrumental syncing is also important as if the instruments in the video don't line up with the ones in the track so they don't look out of place in the song and match up with the music played so they visually make sense to be there.