Adds a link to the mp4 file of gfycat webm, redirects from detail page to actual file page
As of
Add a direct link to the MP4 and WEBM files on gfycat video pages for convenience.
Optionally can redirect after 5 seconds from "details page" to the actual file (with video player) page. But the "details page" doesn't seem to be used anymore anyway.
The source URL should be displayed by gfycat natively now, so that part is now also obsolete (but still included for now).
