Hi Justin,
The media license would allow you to backup local files and System State on a server. To backup another server, you would need the RAWS agent (Remote Agent for Windows Server). This is licensed and installed via a local install on that server, or via a push install from your media server.
To backup applications like Exchange, SQL, Lotus Notes etc, you need again agent again. If not, you'd still be able to backup Exchange for example, but would then have to run scripts to dismount the Information Store, backup the flat files, and then remount the IS etc. A lot harder...
Best bet is to invest in the appropriate agent licenses.
In your case, if you have purchased another full license for BE 12.5, it would be overkill unless you intended using it on that server as a full install, and had hardware to backup too...
Laters!