Will Web-based SlingPlayer work for customers based outside the US?

Yes. While the videos on Sling.com aren't available to folks outside the United States, Web-based SlingPlayer is available. With it, you can connect to your Slingbox anywhere in the world, and you can see the custom SlingRemote for your A/V device.

SlingPlayer Guide, however, is only available to Slingboxes that are located within the United States.