Big ups to the ffmpeg team for making swiss army knife software that probably hundreds of millions of people use every day even though they've never heard of it!

Skimming the changelog, though, this caught my eye:

codec/format registration APIs removed, all formats are always registered

This seems like a bad decision to me. Obscure codecs are more likely to have old unnoticed exploitable bugs, so, for defense in depth, websites processing user uploads using ffmpeg-based tools are well advised to disable support for the vast majority of formats that ffmpeg supports. I assume they can still do that at compile time, which I would guess is what big sites with dedicated security teams probably do, but being able to disable codecs through the API would mean that smaller sites could also implement this kind of security posture while still using distro-provided packages (eg without taking on the burden of building ffmpeg themselves). I hope the developers reconsider this!

(Of course you should also still run it in a sandbox...)