What do "MOVIE DOWNLOAD" sites offer?

My question concerns paid movie download sites such as CinemaNow, WatchDirect…etc.
With fees ranging from $34.95 to $60.00 I’d like to know if these type of sites are true download sites or nothing more than a paid rental site and if they truly have the number of movies available, are the movies something the average American person would want to watch or something on the lines of a documantary of the Slovakian army’s motor pool.
Any info. would be greatly appreciated.