JW Player Demo is broken

https://dador.github.io/JavascriptSubtitlesOctopus/jwplayer.html

It seems that a file the demo relies on has disappeared. Thankfully, [the file in question is well-preserved](https://web.archive.org/web/20170704193118js_/https://content.jwplatform.com/libraries/L7fM8L0h.js)