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Whenever I start a video call on msn my contacts see only black in my video window, why? - black msn addys

I have a Logitech webcam and when I start a video call I clicked and display the two video windows .. In my contacts, they were out the window, but I do not see in black letters that say ManyCam

I know how to operate, but everyone knows where to click to change the webcam .. .. as the place where they make the choice to use the webcam?

Thank you!