I tried contacting the manufacuter and they were not much help. The makers of the software I am using in which I am trying to see more that one vide feed also think that the restriction is Windows, for now I have two different usb to video digitizers by two different manufacturers and that works fine. As I need to see about 8 to 10 video feeds then it looks like I will need 8 to 10 different brands of adaptor. I would have lke to kept them all the same but if I can;t get two working under Windows then I doubt that I will have much chance wth 10!!