Screenshot users display in a web application
<p>What I want to implement is a web application with a video and a button, that every time a person clicks on that button I get/screenshot/anything else their display and save the jpg/or something on the server.</p>

<p>How can I do that? I heard you can't do that with javascript. I had an idea of a plugin/flash application? How can that be done? The application will be done in PHP.</p>
