If you watch it very slowly, the paper initially folds under the mouth and then it blows out straight.

I'm guessing the initial puff creates a high pressure area on top of the paper, rolling it downward and back. Them after the puff has pushed the air away, there is now a low pressure zone on top of the paper which lifts it up as the air below is rushing upwards around the sides of the paper.

That seems like the Coanda effect more than anything.