I remember when Rule/Sparkle was announced the tracklist included "Sparkle" video (CDJapan had the information). So I think avex will put "Melody" video in the final album or maybe not.
Sincerely I prefer Melody. The chorus and the instrumental music are both great.
(off topic) about Rule/Sparkle:
http://www.ahsforum.com/forum/showthread.php?t=84973