Change ffmpeg's --enable-nonfree switch

[ggarra13]

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.

[matteoveglia]

Yeah I saw that too, maybe in the documentation we just need a little blurb about the presence of that flag and maybe an alt command to paste in.