The Beta Server, like the Training Room, is an environment where Paragon Studios publishes game content that needs to be tested before being released to the Live Servers. The Beta Server was implemented in 2010 to test Going Rogue without shutting down the Training Room for months on end. Access to the Beta Server is generally restricted to VIP Players; occasionally the server is completely locked down and only developers and specifically-invited players can access it.
Large-change patches (such as new Issues) generally get presented to the Beta first, then sometimes they are moved to the Training Room for further testing, but often they publish straight to the Live Servers. If the Beta Server has a large-change patch being tested, small or emergency/bug fix patches may skip the Beta Server and go straight to the Training Room since it will match the Live Servers. These small patches are usually already incorporated into the Beta Server, or might also update the Beta Server in conjunction.
Installation is simple via the NCLauncher. An option to install it is located in the game list on the left side of the launcher window. Double-clicking the line will begin the installation prompts.
Similar to the Training Room, the Beta installation might be sped up by halting the download in progress and copying over the files from a Live Server installation and then doing a "Repair" on the Beta installation (right click the Beta install in the launcher window and select Repair). However, depending on how different the files are between Beta and Live, it may or may not save much time or bandwidth.