Instructions: FRAME_NB_VARIABLE_ID is the ID of the variable you will use to set the number
of frames for move picture.
FRAME_NB_ORIG is the token frame number which will be substituted. For instance,
if you set it to 1, the event command will only use the variable as a parameter
if you enter 1 frame in the command itself. This is done so you only need to use
it for numbers over 600.
What is it for? Curious? I used this for Reincarnation Intro since the picture timing doesn't work well with default settings.