fix the links to the demo.

The links currently there are 404 (at least to me, an outside user who
is reviewing video-player-related stuff). Once I finally URL-hacked and
found them, I discovered what a nice player it looked like.
Merge remote-tracking branch 'maxstarkenburg/fix-link-to-demo'

* maxstarkenburg/fix-link-to-demo:
  fix the links to the demo.