[Bug] YouTube player doesn't close when you close the preview window of a YouTube hyperlink.

Okay, just bear with me here. Reproduction steps:

1. Click a hyperlink to a YouTube video.
2. That preview window thing should pop up asking if you are sure you want to visit the linked page. (The answer is always yes, btw. But that is for another thread.)
3. The YouTube video from the link should be at the top of the preview. Start it.
4. Hit the "Close" button for the preview.
5. The preview window closes, but the sound for the video keeps playing.

Sample link for your convenience: