By changing the ffmpeg settings to framerate 2 have achived finally a decent encoding speed https://github.com/jmikedupont2/gpodder/commit/15f275520279e064a9699881ec940850b6d3cdb1
@agates I was fighting with different formats and speed of encoding, this is I found to work. Feel free to change it! At least it uploads and does not get the invalid video.
Intended for all stake holders of podcasting who are interested in improving the eco system