[geoffroy]

got the same problem, it only works with a https address !

[ff_]

Nope. Works even if you use an address without http, but beginning with only "//"

[ufo]

In that example "//" is just another way to say "https://", though.

[hornetblack]

I had the same issue, I think it depends on browser configuration. Some browsers disallow http content on https pages.