Great comment. I wish I was able to write one of equal quality. Your comment convinced me to to shed some light. Everybody be warned I may be biased.
In essence the coup is led by core group that also happens to administer the server where FFmpeg is hosted.
There have been a long standing conflict between Mans Rullgard and Michael Niedermayer. Mans is a quite skilled and active developer and root server admin, but who have bad temper. He seemed quite unhappy from the fact that Project Leader had authority over him, so he specifically targeted Michael who held the title. There have been small stings and mild insinuations for years (including behind Michael's back), using more persistence than strong words. (Such things affect people.) The conflict finally burst when Mans stated he doesn't recognize Michael as project leader. There's been accusation that Michael doesn't follow project rules . Michael immediately requested vote of confidence ( http://thread.gmane.org/gmane.comp.video.ffmpeg.devel/118594 ). It turned out that Michael did follow the accepted and written rules, but not everything other people have been subjected to. The vote took a while. I thought that most of the people voted for option "C" ("I want michael to stay our leader, but to abide by the same rules as everyone else."), but when I counted it today, it was 15x"A" (Stay), 1x"B" (Leave) and 5x"C". Even before getting overwhelming support, Michael agreed to follow same routine as everyone else. Mans since ceased all public and private communication with the community (or so we thought) and even disabled some of the services he hosted (FATE). The level of flames plummeted.
Meanwhile, at the day the conflict burst, (2 Oct 2010) - Attila Kinali (the root admin who bought, found hosting, installed and is responsible for the server) suspended both Mans' and Diego Biurrun's root access, until the matter is resolved. At 12 Oct 2010 Attila restored their root access citing absence of confidence vote (It didn't make sense to me, but he never gave official answer to my objection).
Because Mans has been the primary root admin of the server and he was still absent, it was necessary to find another admin ( http://thread.gmane.org/gmane.comp.video.ffmpeg.devel/119382 ). Unfortunately no replacement was found, so instead we accepted an offer to move the repository on videolan.org server. As they host only git repositories, the project would have to switch to git first.
When the switch is about to happen, Diego "urgently" contacts some developers, and calls them for meeting (on irc). There he manages to convince them (he could be quite smooth talker). Mans is also there. The announcement is signed.
(Comparing the list of voters, I see that around 15 of the "undersigned" people have not participated in the confidence vote, I suspect they may not have been aware of Michael's attempts to amend his mistakes. I know at least one of them didn't. )
On the next day, when FFmpeg completes the switch to git.videolan.org, the root admins create another git repository on git.ffmpeg.org and mail the announce.
Mans gets back on the stage.