YouTube copy at time & start from time

[Yentis]

• Adds context menu button to youtube videos for copying at current time
• Start youtube video from timestamp if available

Also tested and working on firefox

[Andrews54757]

Good idea, but the implementation has some flaws.

1. copy_clipboard should be validated such that non-fs sites can't arbitrary manipulate the clipboard
2. The feature should work with other sources besides youtube
3. Preferably should done without requiring extra permissions. Otherwise, justification will be needed in perms explainer page.

[Yentis]

1. I don't think this is a valid attack surface, any site can already write to the clipboard
2. Why? The feature is only relevant to youtube, there's nothing I can implement for others

[Andrews54757]

Implemented using existing UI elements. Now you can click on the timestamp/duration label to copy a URL containing the timestamp. This works for other websites too. Simply paste in the sources browser to begin playing. Nevertheless, thanks for the suggestion!