Now, I don’t know if this much of a exploit, but you must have heard of the Youtube Red subscription service, where you no longer see ads and can download videos to your device. You have to pay 10 bucks a month, but I found that if you just tap and hold the screen while watching a video, you have the option to ‘save video’- oh yeah, I’m using a Kindle Fire (Generation 3)
I tried to report this to Google support, and they said the best thing to do was to contact Amazon support (?), so that is what I did. After telling them about it, they said the best thing to do is to contact Google support, and then I just gave up.
So, if you have a Kindle Fire, go download your self some free videos.
The Kindle Fire allows you download any video played within its native video player IIRC, which YouTube videos do. YouTube downloaders have existed for a long time, and they’re nothing new. If Google wanted to fix it, they would have.