As Adobe platform evangelist Andrew Shorten points out his blog post, which has considerably more details, the application was built using the Flex 3 framework, Adobe AIR 1.5 and makes use of the Flash Media Rights Management Server (FMRMS) to DRM-protect content which is downloaded to the user’s desktop. Since it is built using AIR and Flex, it runs on Windows, Mac, and Linux operating systems (see our recent Linux announcement).
From the press release:
"Now, the new download manager allows users to view their favourite BBC shows, online or offline, with a high quality solution across operating systems."
Important note: Similar to the web version, The BBC desktop iPlayer is only available to UK audiences and can only be accessed within the United Kingdom. According to this BBC iPlayer help page, they are looking into adding additional region support in the future through BBC Worldwide. Andrew has a few more images on his blog post in case you are curious what it looks like.