As of April 25, 2024 it appears YouTube has changed something. Downloaded videos including 360p are replaced with a 5min video containing the static message "The following content is not available. Watch this content on the latest version of YouTube".

Leaving 4 stars because this free extension has worked great in the past, and I hope it will work again soon. I only want 720p but the option for 720p is no longer there and the 360p version ends up being the above message.