Prevents auto-play HTML5 videos in new tabs on any page (not just YouTube) and pauses videos when leave/switch/change the current tab, to prevent any video playing in the background. This auto play blocker is an alternative to Click-to-Play / click to play. On some times like YouTube, click twice to begin first playback — From Dan Moorehead (xeonx1), developer of PowerAccess™ (http://PowerAccessDB.com)
< Feedback on AutoPlay Disabled for HTML5 Videos + Pause on Switch Tab
To fix Unpause by space: add the following lines to the script code from here: https://pastebin.com/s3qmDqW7 Works on pages like youtube.com/watch?.... .