Avidemux is a very popular cross platform video editing program, ideal for all kinds of video file conversions, appending, cropping, cutting etc.
It is notoriously difficult to build from source and unless you are the developer with easy access to all the dependencies required to build it then it makes sense to find an rpm version to suit.
Finding an good installable version has proved a little elusive for Centos 6/RHEL because of its huge dependency requirement but I finally managed to track one down fom the naulinux-school repo.
To install it first make a naulinux-school repo file
$ sudo vi /etc/yum.repos.d/naulinux-school.repo
See vi and vim commands.
Enter into the file
Save the file (set disabled)
$ sudo yum -y --enablerepo=naulinux-school install avidemux
Run it with
Fluxbox users can put in the /home/<user_name>/.fluxbox/keys file
Mod1 a : ExecCommand avidemux
To run it with 'Alt a'
See Fluxbox key bindings for more.