See the full written article here: http://www.asxmarketwatch.com/2012/06/lets-learn-amibroker-how-to-scan-the-market-for-buy-and-sell-signals/ , also with the AFL code used in the video.
Learn the Amibroker Basics – how to scan a stock or portoflio for buy and sell signals. We also go through some basic Amibroker Formula Language (AFL), how to use Amibroker to scan a market with your chosen rules and get results in minutes.