How does this website make money?

I wanted to download youtube videos for my kid. I found a site where you just put the link and they make a file for you and you download it. It is perfect, no limit to how many videos you can enter the link for downloading.

I won't post it just in case they are doing something blackhat to not expose them but its easily found on google.

The interesting thing is, I can not find one ad at all and I checked every page. With no ad's and no limit on how many youtube videos I can download before I pay, there is no payment, what is the point of that website? Is someone just being generous and they made it for free? I don't get it

Well, maybe he does it "for the community"
Sometimes... happens

It could be a new site and the owner is still gathering his traffic, at some point he will start showing ads!