What a fight!
In order to develop the new video thumbnail generator for BelaCena v2, I just spent the last 4 hours struggling to build ffmpeg-php on Leopard. Goddamnit. These things make me miss Linux :)
Anyway, off the top of my head:
This finally worked after struggling with a ports install of ffmpeg, a php-version mismatch (I have a ports version and the one bundled with osx) and a few tens of minutes fiddling with those lousy ffmpeg configure switches and libswscale...
argh!