"A lip dub is a type of video that combines lip synching and audio dubbing to make a music video. Usually made by filming a group of people lip synching while listening to a song or any recorded audio then dubbing over it in post editing with the original audio of the song. Lip dubs can be done in a single unedited shot that often travels through different rooms and situations within a building, campus or even a city."
I first saw a lip dub in 2009 or perhaps early 2010, it was sort of a takeoff on flash mobs. Recently I was sent the link to a truly amazing lip dub done in Grand Rapids, Michigan and set to Don McLeans American Pie.
I highly recommend taking a break from what you are doing to marvel at and enjoy the Grand Rapids LipDub.