Srsly its too hard to do unless ur uber because each web cam has a different input code to to it on, know wat u can do is get a program wats like screen sharing for mac but a windows version if u have access to their computer u can authorize ur computer but when u r doing it it appears on there screen as well. Now wat i have said is devious but all legal technically apart for authorization part but there is another way to do it quite simply but it is fully illegal so im not going to say anything i dont know how it works i have seen it work tho