At first it wasn't known whether the MPlayer2 fork would survive and continue to be maintained after the change happened last year, but it's managed to stick around with active development.
Features that the MPlayer2 developers claim for why they are better than the original MPlayer include improved VDPAU video acceleration, better pause handling, better Matroska support, no FFmpeg depdence, OSS4 volume control, and many other improvements that were never made to the original code-base for the media playback project. MPlayer2 also killed off MEncoder, the internal GUI, and setup other differences.
As far as what the MPlayer2 developers have been working on recently, there's still commits happening but not on a daily basis -- the last commit at the time of publishing was 11 days ago. Among the work to MPlayer2 Git includes HiDPI / MacBook Pro Retina display support for the player's Cocoa code, other OS X specific changes, workarounds for PulseAudio timing bugs, removing support for IRIX, removing support for OS/2, and lots of other miscellaneous changes. So they're still working on the project, but no exciting breakthroughs (aside from possibly this yet-to-be-committed Wayland support) have been made in the past couple of months.
The developers mostly responsible for MPlayer2 at this time are Stefano Pigozzi, Uoti Urpala, and a developer commit under the name wm4.
Those wanting to learn more about this lightweight, customizable, cross-platform open-source video player can visit MPlayer2.org.