As @stefan-lund already mentioned the device tag has been replaced by the WebRTC specification.
Opera has a dev build available at http://dev.opera.com/articles/view/labs-more-fun-using-the-web-with-getusermedia-and-native-pages/ which supports WebRTC.
Chrome should get support in early 2012 (http://techcrunch.com/2011/11/24/chrome-getting-native-gamepad-webcam-and-webrtc-support-in-early-2012/)
If you just want to receive a video upload you can also use the Media Capture API instead, which is a special type of the input type=file
element.
<input type="file" accept="image/*;capture=camera" />
Browser support for that is covered here: The Media Capture API - any existing implementations?