COPYING.txt is the GNUv2 License for the following included tools:

dvb-mpegtools
dvdauthor
ffmpeg+x264+liba52+faac+faad+lame+libogg+libvorbis+libdca
mkisofs
pnmcrop
y4mtoppm
yuvcorrect
lsdvd
tccat

Source code is available at the websites linked in the "Credits" section of the Users Guide.

ffmpeg-r9226.diff.bz2 is a bzip'd diff of the Techspansion/VisualHub-specific edits made to ffmpeg's source as of SVN revision 9226.
/usr/bin/svn -r 9226 checkout svn://svn.mplayerhq.hu/ffmpeg/trunk ffmpeg