Default behavior extension should only run on the tab when clicked. https://i.ibb.co/L9zdQsY/image.png if it's not working as expected remove permissions under about:addons.
This behavior works better on MS:Edge.
Prime video is also working fine for me. https://i.ibb.co/sjMP70Y/image.png
I'm not experiencing any issues with bing.com, the videos seem to be mostly youtube videos and they load as normal. Do you have other extensions installed? Also because MS love proprietary nonsense. I recommend using User Agent Switcher to make all MS junk to use Edge's UA.
Further changes to allow per URL stuff, and caching sites requires more permissions. This was originally meant to be low permission, and the smallest footprint volume control plugin.
Please contact me in the Github repository via the issues tab.