As they state on http://www.redlaser.com/SDK.aspx :

"WARNING: 10/14/2009 The RedLaser SDK currently uses an unpublished function to access video frames. Very recently, others have indicated that this will likely lead to rejection of any application using this function, including any application with the RedLaser SDK. We are working hard to find a solution, as we believe there is great potential for this technology on the iPhone. Please take this into account when considering use of the RedLaser SDK."

So they probably analyze a lot of different video frames before finding an accurate one.