You will want to whitelist any video sites that you want to allow to autoplay. Any time this script stops a video from autoplaying, it will output a line to the console (as shown in the attached screenshot). You can use that information to whitelist it.
With Tampermonkey, you may need to enable logging at Debug level to see output in the Chrome F12 console.
With Firefox, you'll need to view the Browser Console (CTRL/CMD + Shift + J)
