• about:config
  • Search for media.autoplay
  • Set media.autoplay.blocking_policy to 1
  • Set media.autoplay.default to 5

Bonus: How to set default volume level: media.volume.scale set to .25 (or other sub 1 number)

• MacOS configuration

  settings > wifi > known networks > <your_ssid> > ... > network settings > low data mode

• Enter "about:support" as URL and select the "Open containing folder" button. You can reach it using Menu "Help" -> "Troubleshooting Information", too:

• MacOS default path: ${HOME}/Library/Application Support/Firefox/

• WARNING: Close the targeted application before launching this following command:
  open -a "Helium" --args --make-default-browser && open http://perdu.com

Pour régler une télécommande universelle (5€ chez Action) pour une TV GRANDIN LD224GTB:

• Allumez l’appareil
• Appuyer sur "Set" jusqu'au clignotement (mode apprentissage)
• Entrer Code Clé 0400