[dozzie]

Yeah, exactly the same work as you would need with an OS-supplied package manager to build your own package. For some reason, though, this is considered sexy, while doing the very same thing for RPM or DEB is regarded as boring and troublesome.

[smilliken]

You don't need to write your own expression for ffmpeg.

To install it with apt: `sudo apt-get install ffmpeg`

To install it with nix: `nix-env -i ffmpeg-3.4.2`