From what I understand about packaging and digging through the source and configure options, this functionality does not work because the program was packaged as a Debian Free Software Guidelines (DFSG) compatible package. You know, the reason why you need to install the
(k)ubuntu-restricted-extras meta packages.
The following lines in the file
debian/rules in the source package seem to be the culprit here:
DEB_CONFIGURE_EXTRA_FLAGS := \
Which literally disables the complete functionality you are looking for. I checked with a WEBM/VP8 and Theora video file without audio that I converted by myself with ffmpeg - doesn't work.
I could only find the dfsg packages on lauchpad and searching on the Internet for "ubuntu gimp-gap" packages only brought up the same results.
Your only choice at the moment is to repackage the package yourself (see the packaging guide). Throw out all the lines mentioned above and probably modify the first line of
extern_libs/configure_options_ffmpeg.txt to look like this:
--enable-shared --enable-static --disable-mmx --enable-nonfree --enable-libfaac --enable-libfaad --enable-libmp3lame --enable-libx264 --enable-libxvid
Besides: Please update to the current LTS (12.04).
Extract video range feature is broken in Gimp-GAP
Mplayer based extraction does not work with Mplayer2 or mpv