This package uses FFmpeg. You need to install it in you system.
On Ubuntu 9.04 you have to execute:
sudo apt-get install ffmpeg libavcodec-unstripped-52
On other linux system compile FFmpeg with flv and mp3 support.
If you are using zc.buildout to manage your project, you can do this:
Add stxnext.transform.avi2flv to the list of eggs to install, e.g.:
[buildout] ... eggs = ... stxnext.transform.avi2flv
Re-run buildout, e.g. with:
Finally go to 'Site Setup' -> 'Add/Remove Products' and install stxnext.transform.avi2flv.
AVI clips will be automatically converted, so no special attention by editor is needed.