Yes, this issue is reported and discussed (but not solved) in this post. There hasn’t been a follow up on the suggestion there. We’ll try to re-encode an mp4 which doesn’t start at 0 on Windows (in the JMMF Player) and see if there is a way to ensure the file always starts at 0.
If the performance of the JavaFX Player is acceptable (it has improved in recent versions), this might be a cross-platform alternative for the default players?
-Han