Odroid N2+ .mp4 and .mkv not working with CoreELEC 19.4-Matrix_rc2

in which position do you have boot select switch on N2+?
Left(SPI) or right(MMC)?
https://wiki.coreelec.org/coreelec:odroid#odroid_n2_n2

You should try to update petiboot to latest one 20220204
https://wiki.odroid.com/odroid-n2/os_images/petitboot#upgrade_mode

Petiboot images could be found here:
http://ppa.linuxfactory.or.kr/images/petitboot/odroidn2/

We could repeat the same issue on 20211112 version, so don’t use it.