This is happening because the video box inside the page is not rendered by the web-browser but by the quick-time plugin. hence the web-browser has no information of the graphics content on that region. it would draw blank box.
Now the one person who knows everything about all the graphics content on the screen is the Screen
itself. so you can try Graphics.CopyFromScreen
method. It has some drawbacks though. for once, it would capture everything on screen including task bar and title bar. second it will capture only the visible part of the page. if the page needs scrolling, or you need full-page screenshot then we have a problem.
we could have workarounds though. the taskbar/titlebar can be cropped off by carefully calculating the rectangle area out of the whole screen. similarly the page can be programatically scrolled, recaptured and images joined to full-page view.
as for the actual implementation, i am fairly optimistic about capturing perfectly sized rectangle out of the screen. i can help with code if you ask. try first (tip) . as for the second part of scroll-capture-join, it would be quite tedious i am sure, but achievable.