Running ffmpeg on a .flv file failed and produced an SELinux denial: "SELinux is preventing /usr/bin/ffmpeg from using the execstack access on a process." I don't know whether ffmpeg is doing so legitimately, but if so it should be allowed. If not, a bug would need to be filed with RPMFusion (the packager) or the upstream maintainers.
SELINUXTYPE=targeted ffmpeg-0.6-4.20100704svn.fc14.i686 selinux-policy-targeted-3.9.7-18.fc14.noarch
*** This bug has been marked as a duplicate of bug 652297 ***