Embedded playlist won't load in both Chrome and Firefox on Linux (Ubuntu)

[macaronii]

In both Chrome and Firefox on Ubuntu all I get is a placeholder with an error message where there should be an embedded playlist.

Chrome error message: "open.spotify.com refused to connect."

Firefox error message: "Unable to connect"

It tried this using Chrome in a Windows 7 virtual machine and it worked fine.

Is there any way I can fix this?