This is just my attempt to explain the current situation. Please contact Andrea Mennucci directly with package questions. The latest version of this FAQ (or a pointer to it) should be at http://people.debian.org/~mjr/mplayer.html It was announced to debian-legal on 2005-04-20.
Yes, since Oct 2006. It may be part of the next release Debian 4.0 (codename "etch").
There were problems with copyright and patents (according to this summary of the history).
(from debian-legal Feb 2005 threads unless marked)
And what about patent problems? It looks like - at worst - mplayer as packaged now would introduce no new patent problems to debian. If you know otherwise, or can work on the patent problems shared by other packages, please act!
It's in unstable. Previously, Jeroen van Wolffelaar reviewed it on debian-devel.
See Matthew Garrett's description of ftpmastering. The NEW queue summary suggests it could take up to 3 months.
One theory: mplayer.deb seems to be a "tinderbox" - Anyone who has prolongued exposure to it gets frustrated by the legal grey areas and its history, so they start flaming innocent bystanders for being wary. This writes new chapters of bad history and "dries the tinder" more. Users and other developers are wary of mplayer because of this history, so probably treat it differently to other packages, increasing the frustration of the developer and thereby helping to start the flames. Sometimes they try to be kind while being wary, which makes the flames hurt more. (From this list post)
Work on software patents if you can. Please review the package if you have time, especially looking for problems like those which stopped it before. Please watch debian-devel-announce or debian-devel-changes for developments. Please don't flame anyone.
The main archives. Previously, it was available direct from the packager at his mplayer download area.
Ask the packager first, or debian-legal for licensing questions if you prefer.
Email me with comments or patches to the bare html, please.
1 November 2006, MJR
So far, some patches from Ken and some from A Mennucc. Bugfix from Georg Neis.