Get the Riva player.
http://rivavx.de/index.php?downloads0&L=3
Scroll down to the free one at the bottom.
After you install it:
Get the Firefox extension. Video Download Helper
https://addons.mozilla.org/en-US/fir.../type:1/cat:38
This puts an icon in your toolbar. When you watch a video that is downloadable (so far they all are) it starts to rotate. Click the name to download it to your Riva player folder.
Now you can watch it without your browser.