A: None of them was an advert (if you don’t count movie trailers).
I’ve taken to bookmarking excellent viral videos when I see them. Reason being, whenever I’m asked which viral videos are my favourite (journalists, conference panel moderators and analysts seem to ask this most often) I can never seem to recall one.
Maybe my recall for “virals” is like jokes – I’ve basically got three slots in my long term memory and once they’re full, I’ve not got much to go on.
This obsession with “viral videos” is a legacy thing, a hangover from the channels model of media. People projecting their wish that the world were still simple eneough that a 30-second video (easy concept to understand, recall, make money out of) still sat at the centre of it all.

You saved the best insight for the last paragraph there, Mr Mayfield…
Thanks a lot, Mr T…