To quote from SubJunk on the PlayStation 3 Media Server v1.50.1 Build 61 changes:
This build functions as the bleeding-edge testing version of PMS. Here you can find features and bugfixes before they are added to the official version, and sometimes ones that never will be. Using this build is mostly a way for you to see the newest developments and to help us by providing feedback.
Changelog 1.50.1 Build 61:
Switched from using Git source back to SVN
Synchronised with official r1024 from r1014
Updated MediaInfo for Windows and OS X to 0.7.53 from 0.7.52
Updated MPlayer and MEncoder for OSX to SB22, in sync with the Windows version.
80w ago - Following up on his previous release, this weekend PlayStation 3 developer SubJunk has updated PS3 Media Server to version 1.50.0 Beta 2 for Windows, Linux and Mac which includes several bug fixes as detailed below.