If you're the Beeb, apparently you can pull off this sort of thing.
I thought I'd add a bit of background. Like, why this video -- and why this song, of all the songs to choose to make an elaborate music video for? The video came about because the BBC has just launched a new service called "BBC Music." And as for this song, clearly the oft-repeated line, "God only knows what I'd be without you?" is the foundation.
What helped get the participants, too, I suspect is that the song is going to be released as a single in order to raise money for the charity, Children In Need. Given the initial response, it should do well in that regard. The video was only released on October 7, and already its had over 6 million views.
If you want to know who all the performers are appearing in the video, you can check it out here. (I'll start you off, the fellow you see below is Pharrell Williams, who even if you don't tend to put music on your radio or cell phone, you might recognize as one of the new hosts of NBC's The Voice.)