sentences:  Although Moonlight is free software, the final version was going to use binary-only audio and video codecs provided by Microsoft which will be licensed for use with Moonlight only when used as a browser plugin (see above).The Windows media pack is not distributed together with the Moonlight plugin but the first time when media content in Silverlight is detected the user will be prompted to download the pack containing the codecs used in Silverlight directly from Microsoft.Self built versions could still use the FFmpeg library and there was discussion about adding GStreamer support as an alternative to using Microsoft's binary codecs for those who wish to use GStreamer instead and also for use when used outside of a browser.