Followed by Chrome and Opera, Mozilla is working on adding getUserMedia API or Webcam and Microphone support for its browser Firefox. The latest Firefox Nightly (Firefox 17) build has already supports getUserMedia API and allows web apps to easily access a user’s camera and microphone without the need of a third party software or plug-in.
GetUserMedia API is a part of WebRTC project which will enable real-time video, audio and data connections from within the browser (WebRTC isn’t fully ready for mainstream use).
In Firefox 17 Nightly, getUserMedia API is off by default. You need to enable it by going to Firefox’s about:config page. For that,
Type about:config in the address bar and hit Enter. Search for “media.navigator.enabled” in the filter field. Double click “media.navigator.enabled” to make its boolean value “true”.
[If the entry is missing, open "about:config" page and right click on an empty space, select 'New' and then 'Boolean'. Add media.navigator.enabled and set its value true]
Mozilla has a test page to test getUserMedia feature. Also, note that, gettUserMedia in Firefox is in its very basic stage and they don’t have any authorization feature as in Chrome and Opera. You can read more about this feature at source.