Being able to download the videos and keep them is important for me. I wouldn't like to pay for something that I can watch only one time because I like to be able to watch the videos again and again several days, months or years later. I'm even inclined to download the free streaming videos that I like because it sometimes happens that a streaming video unexpectedly disappears for any reason: closed site, decision of the creator...
Furthermore, I don't want to have to depend on my Internet connection for the viewing: sometimes my connection is laggy, sometimes I don't have access to Internet at all. Having them on my hard drive is much more reassuring and convenient for me.

I always download my videos on Clips4Sale. I can't compare with the other ones because I don't know them, but most of them are relatively recent and I prefer to place my trust in C4S which I've been using without any problems since 2005 than giving my personal information and money to these new C4S-imitators. And by giving money, I mean credit a large amount of cash at one time and then consume it very gradually over several months, which is a very convenient method that I use on C4S because it's technically possible (it's called "Clip Cash Card") and because I trust them enough for that.