by Matt Bury.
Hi Tomás,
Unfortunately, there is no easy upgrade path for the Media Player plugin module for Moodle 2.4, as far as I know. I know that at least one other developer has tried without success - It's just too complicated and difficult to deal with the file dependencies, playlists, etc. with Moodle 2.x's files manager.
Please also bear in mind that there are still backup and restore issues in Moodle 2.x, e.g. https://tracker.moodle.org/browse/MDL-28526
It may be a good idea to do a "slow migration" from 1.9 to 2.4, gradually moving courses across and testing that everything works as you go and then fixing or developing workarounds for anything that doesn't. A lot of work and frustrating though