Control Youtube with other devices.
Simply install the extension and open a Youtube video or playlist. A new button will be added to the settings bar of your video. Enable Youtube Connect and either scan the QR code or open the remote application and enter the 8 word mnemonic to connect to your session. This is a side project and is not perfect, but good enough for most use. Feel free to view the source and make contributions if you wish (or fork the project).
If Youtube connect is not enabling in the player, it likely means that the API server has shut down. If that occurs and you need to continue using the extension, you may modify the extension to use an API server you run yourself (based on the available source code).