Just saw the notification for this in my Youtube Studio. For now it seems as if this setting is turned off by default, but for anyone like myself who uploads videos to Youtube, I recommend checking that they don't decide to toggle this on for you in the future.
It's going to be fun navigating Youtube in the future when 95% of it is robotic videos with 95% AI comments below to match.
Honestly, I wish it was the other way around, a video-to-text service that writes a good synthesis, a complete transliteration with formating, or even an expanded version, with screenshoot images if deemed necessary. So many videos could be turned into nice essays and commentary.