[pmontra]

Most of them will say, "I need to see this site, who cares about fingerprints." Some will notice that they're on their screen anyway, a few will know what it's all about.

Maybe "it can be used to display 3D graphics and to track you", but I expect that most people will shrug and go on.

[bcrosby95]

You could maybe display the request in the canvas instead of a popup. If the user can't see it, they'll never say yes.