I just noticed that AdBlock Plus for Firefox does a much better job at blocking commercials on videos than AdBlock Plus for Chrome does. AdBlock Plus for Firefox does a superb job - at least at Engadget.com - blocking 15-second commercials. I did not even know Engadget videos had ads until I watched them in Chrome.
I hope that AdBlock Plus for Chrome will eventually do as great at job at blocking those useless, annoying commercials.
Above all, thank you to the developers!