Official ffmpeg vs alienbob ffmpeg

I realized while screwing around with some ffmpeg encoding that alienbob's compile of ffmpeg seems to have many more codecs compiled within it using more flags than the standard slackware ffmpeg in -current.
I'm wondering if there are ways to 'activate' those additional codecs in the standard installation without having to recompile or use alienbob's. Nothing against either options as I've been using Bob's for quite some time it seems but I'm just wondering why they weren't included in the first place (libx265 and aac to be specific)

I always assume I'm doing something wrong ;p