Change ffmpeg's --enable-nonfree switch

Using this switch prevents redistribution of binaries. While for Linux and big studios this is no big deal, if you want to build on Windows or Mac and distribute binaries ti is.

Start by locating the xSTUDIO build configuration that passes ffmpeg's --enable-nonfree switch and review how Linux, Windows, and Mac builds use it. Determine what change would permit redistribution of binaries on Windows and Mac, then verify the affected build configurations no longer require that switch.

Written by the indexing model from the issue text.