Attila Kinali wrote to the MPlayer development list, "I got a mail from a certain project leader, claiming to be backed up by MPlayer developers, containing legal threats that border on duress.
Although I got used to get such threats from companies who thought they could stop the development of a codec by intimidation, I am definitely not used to getting such mails from project members, much less from people I once considered to be friends.
In order to protect myself from getting drawn into a pointless legal battle between grown up men who behave like children in a sandbox fight, I decided to leave the MPlayer project."
As a result, he's packing up and will no longer be involved with the project. He's shutting down all of his MPlayer services in a week, including the main MPlayer server. Though he has offered in kind to send this server to another MPlayer member so that services can be restored, if anyone accepts.
Details beyond that are unknown at this time but the original email can be found on mplayer-dev-eng.