I'd love to believe these were real people and not actors, but several distinctive features of the location make it clear that these viral ads were shot on the backlot of Wimbledon Studios. (For instance, the 'District Taxi' rank, which has appeared in countless episodes of The Bill).
Are we to believe these supposed members of the public drove onto a closed set, not accessible via the public highway, without twigging that something was up?
Congratulations on so perfectly harnessing the power of YouTube! A very merry Christmas to everyone involved in this fantastic festive morale-boosting triumph of a video, and to all of your families – you have really earned it.