The latest version of the Firefox Beta branch can be downloaded from Softpedia
Mozilla has officially announced that the first Beta release in the Firefox 22.x branch is now available for download on the Linux platform.The Linux binaries for Mozilla Firefox 22.0 Beta 1 have been made available and you can download it now, without having to install anything.
The new and improved Firefox comes with some nifty new features, which include WebRTC enabled by default, improved HTML5 audio/video playback rate, better WebGL rendering performance, word wrapping for plaint text files, better memory usage, and a new Web Notifications API.
A detailed list of changes can be found in the announcement.
Download Firefox 22.0 Beta 1 right now from Softpedia. Remember that this is a beta version and it should NOT be installed on production machines. It is intended for testing purposes only.