media/youtube.lua: Use HTTPS if input URL uses it
Use HTTPS throughout the operation if the input URL is an HTTPS URL.
The script previously made the video info queries over the HTTP even if
the input URL was given as an HTTPS URL.
Note that the media stream URLs are only available over HTTP; the
service apparently supports HTTP media stream transfers only, and any
attempts to force HTTPS will result in HTTP/403.
Other:
* Cleanup and revise for readability
Signed-off-by: Toni Gundogdu <legatvs@gmail.com>