Content is too big or smalll to fit on the prezi canvas, won't let me add or change anything!

My prezi won't let me insert a video or do anything...
I've tried deleting things but it keeps telling me the content is too big or small to modify on the prezi canvas. I'm literaly done with the presentation, I just need to add one more video! please help! http://prezi.com/fnmhzz2b42af/edit/#1...