To date the proxy is functioning fine
The only issues presently seems to be MAC users, so if you are struggling then we suggest trying a different browser.
In fact this usually cures most problems. Presently I recommend www.maxthon.com
Just for some background information, generally either the BBC the Browser or JAVA will update their application which then will often result in not being able to access the iplayers.
As a result if you struggle I recommend you test out another browser but FYI IE and Chrome operate at the system level of your PC and Firefox Maxthon and Opera operate within the browser. Which is why I would prefer to recommend FireFox and Maxthon.
If you prefer to download programmes with the BBC desktop to watch later the proxy needs to be set at the system level of your preferred browser.