Hey all, this is a good catch.
The builder's 'Preview' functionality is our version of a 'testing environment'. But, because Preview loads over https, and http content will not load (as it throws a mixed content error). The jquery and modernizr references in my script were both referencing http versions, which caused the animations to break in Preview.
I've updated my script by removing the http references (see here), so now the animations should work as expected in Preview!
Give it a try and let me know how it goes!