Here
https://wiki.recalbox.com/en/basic-usage/features/boot-videos
is described how you can add new Videos, which Video will be played and set the Playback Time.
It is not described how you can turn the Video completely off.
I think I found a solution for the problem:
You must edit your "recalbox.conf" File
Go to A - System Options -> ## Splash screen duration
and set system.splash.length=1
