Found this one on how to use bootanimation or bootvideo:
To enable video boot a line in the build.prop needs to be edited/added:
service.bootvideo=1 this enables the bootvideo, service.bootvideo=0 makes use of the normal bootanimation.zip, same for not having this line.
The actual bootvideo is as said a MP4 file named bootvideo and is located in the etc folder of the system partition - if not you need to make one 
Any resolution the box supports can be used here but for obvious reasons it should be only as long as the actual boot might take.
There should be a file bootplayer inside the /system/bin folder - this is used to play the video.
In case it still won't work with all the above files you need to add a service in the init.amlogic.rc file of your kernel.
service bootvideo /system/bin/bootplayer /system/etc/bootvideo
class main
user root
group system
disabled
oneshot