hi ! the note spacing works by setting the highest and the lowest note to the margins and evenly spreading out the notes between them so if u have really high and really low notes it could get a little cramped,. i'd probably try moving up/down the track with the lowest/highest notes an octave for the midi so the range of the notes is smaller.
animated backgrounds are not supported right now, i think people just do a solid color and chroma key it in a video editor