ffmpeg is a command to record, convert, stream audio and video (source). I m gonna using it to convert a movie dat file into mpg that will be burnt as a vcd by k3b.
Here is the command
Now in order to use k3b to burn the mpg into vcd, check if the k3b has vcdimager.
If you got a result like vcdimager-07.24 you already have it. If you don’t install the vcdimager from www.vcdimager.org
Now the k3b can burn it into vcd.