This is one of the coolest new things I have seen in the past year or so. Most of you have probably seen this video before, but what you haven't seen is the Viddler player. Hover over it and check out all of the great features, including the ability to leave comments embedded at certain times in the video. I've left some of my own already. They're represented by the little white dots on the status bar.
Should the pop-up comments become distracting, you can simply shut them off. You can also email the thing, grab embed code, and switch from streaming to download (just under the status bar), depending on your internet connection.
YouTube should be shelling out for these guys any day now.
Anyway, just thought I'd share. Play around with it by leaving your own comments. Just click on the green plus sign on the scrubber. You may need to register with Viddler first (I don't know), but it's well worth it.