Go to http://developer.yahoo.com/yui/theater/
Search within that page for "Douglas Crockford", you'll find direct download links for these and other videos by Doug.
In Safari you can click play on the video, open the Activity window (Cmd-Alt-A), then snag the URL the actual .flv file is being pulled from.
Could you paste the URL here? I tried finding the .flv file in the activity window, but I couldn't locate it.
Search for "Crockford" on the YUI Theater homepage. The videos are available for download in M4V format, along with zipped PowerPoint slides.