Fixed: on some video pages the menu could offer a generic "Stream" download
instead of the list of qualities. That link points at one internal piece of
the video rather than the video itself, so it produced a broken or silent
file. Those links are no longer offered.

Improved: the popup now loads the available qualities as soon as you open it,
instead of waiting for you to press a button.

Improved: when the Downloader Pro desktop app isn't running, the popup now
says so clearly, instead of quietly falling back to showing raw stream links.