Okay, seems to do the trick.
I first installed curl via homebrew (not sure whether that is necessary, make sure its in the path before system curl which homebrew doesnt do automatically)
then it is simply a matter of creating/modifying your curl config e.g. using atom
atom $HOME/.curlrc
and appending the line
insecure
save, quit all terminals and now I can build FFMPEG@0.2.4
@oheil - since it is not an Pkg3 issue - is it a FFMPEG issue then? Hm, I did not have a user-level curl config before and the vanilla homebrew version alone did not resolve it either - so it is a certificate problem but why? Seems to happend to a few people…