Leafpad is probably not going to be able to save the file because you need root privileges (unless you start it from the root shell, thanks for clarifying). I use nano, but that's not installed by default. The easiest way to do it is probably to edit the file and save it to MyDocs, and then copy it as root (from rootsh). Edit: Or to run Leafpad from rootshell.

And yes, that should work for playing them sequentially.