Modified the YT-downloader script

What it does:
For some songs it does work as expected and opens the dialog prompt: watch?v=0KSOMA3QBU0
For others, it redirects me to their "convert and download page", even though the response JSON has the link for that: watch?v=450p7goxZqg
For a possible third scenario, it redirects me to a page with a converted video, instead of initiating the download
Also, even in the cases where it works, it does, even though for an instant only though, open a new tab and then close it, although that may be because I did not give the request any parameters. That is because I got nothing from the "send()" function's documentation.
This is obviously because of my limited knowledge of JavaScript. So please fix this when you have time.