The only thing to work for me was to use a Firestick. You can't be in incognito mode. Go to Settings, Display and Sounds and click Enable Display Mirroring. Then you need to connect phone to Firestick. Mine has a wireless projection feature in the pull-down menu. This will project entire phone screen to tv. Then just select full screen on video you're watching and enjoy!
The only thing to work for me was to use a Firestick. You can't be in incognito mode. Go to Settings, Display and Sounds and click Enable Display Mirroring. Then you need to connect phone to Firestick. Mine has a wireless projection feature in the pull-down menu. This will project entire phone screen to tv. Then just select full screen on video you're watching and enjoy!