https://news.ycombinator.com/item?id=28569079 https://news.ycombinator.com/item?id=28569079 > 2. If you have set your history to expire after some amount of ti

https://news.ycombinator.com/item?id=28569079 https://news.ycombinator.com/item?id=28569079 > 2. If you have set your history to expire after some amount of time, it will start re-recommending videos you've already seen once it has forgotten you have watched them.