The best way to do this is to use another PC/Laptop (not on the same network as your stream) and input the screen of that machine via one of your capture devices. Next best is to use the vMix Screen Capture utility. This needs to have both your machine and the PC/Laptop that will browse for the webpage on the same network. (You can of course set up port forwarding and NAT on a router if you use different networks). However, if you are going to feeed multiple screens you may need to get the vMIX computer to feed another device that can then Multicast to your screens. The aVerCaster Duet is an example of those.