When you kill the app, does it disappear?
Discussion
Yes
For my situation, It does not go away. Just retested. Opened amethyst, scrolled through until an MP4 started. Checked the media badge was present. Killed app. Media badge remains.
I have an issue where the content is unavailable and the media badge appears to be trying to load, but is unresponsive to a "kill" swipe (i.e. swipe right/left)
Kill the app via force close in settings
I have a media badge stuck now. Amethyst was not running. Swiping did not kill it. Long press in badge and an android control popped asking to "remove this notification from Amethyst". Pressed yes and it went away, however, I feel something is hanging after media plays and remains after app is killed.
Humm... I will investigate this further. You can always go to Settings/Apps/Amethyst and force close. That gets rid of anything running.