reduce requests, make loading screen functions & vars

There is still a problem with these changes with the loading of media assets.  We are running into this bug I believe:

https://code.google.com/p/chromium/issues/detail?id=234779

While the numbers of requests in chrome network view is reduced and no duplicates are occurring, most assets are blocked from loading and held in "pending" state until all previously loaded assets are played entirely.  

Easiest way to see this issue is to load the page and scroll down to the second video area (the zoom map), it will remain as a black screen unless you scroll up and let the chapter-title video above it play through.