I’m from the team that developes BuddyPress Media.
Till now, capturing a video involved expensive (in various ways) setups. It depended on flash and silverlight which could reach the hardware (mic and webcam) . Html5 is the way to go, now. However, the support isn’t wide enough. This might help you: https://stackoverflow.com/questions/7386675/video-capture-in-html-5.
If you do wish to develop such a solution, do get in touch with us at rtCamp http://rtcamp.com/contact