Does Google drive rather than Drop box work for you?
My version does not work for me at all in Firefox, but yours does.
However both Gd, and Db versions work for me in Chrome, but not in Canary ... I'm guessing some sort of flag there.
Internet explorer runs yours, but not mine, and Safari doesn't run anything.
Ipad3 on the other hand runs everything.
Has something been updated that hasn't propagated to the other browsers?