media-video/ffmpeg: update maintainers, fix open bugs, undo last-rite

After discussion with members of the Broadcast team, two new maintainers will be assigned to this package. Additionally, the two major bugs in the ebuild are fixed by this MR.

With this, all requirements are fulfilled to undo the last-rite of the package, which is the last step in this MR.

NOTE: I didn't test the bugfixes made in this MR. This is left to the maintainers of the package.

Closes: #151 (closed), #150 (closed), #143 (closed)