I mean 240p is complete insanity (really I have no idea how you can stand looking at that) but if your limit is 19MB, you've mapped 1:24, and if your video is that long, you can easily reduce the filesize at 720p (I hope you really have a 720p video instead of something larger) by reducing the bitrate and removing the audio track (which you should do anyway). I think I've seen a thread about how to do that but I cba to find it so look for it yourself
if you haven't mapped all of the song yet, do that before messing with the video