HTML5 WebPage Activity Recording using RecordRTC

You can resize image or above header and drag/move video:

There is another demo, that allows you record drawings!

var recorder = RecordRTC(document.documentElement, {
    type: 'canvas',
    showMousePointer: true
});
recorder.startRecording();
recorder.stopRecording(function(url) {
    window.open(url);
});