Looking for a background information on the BM algorithm, I discovered several neat sites explaining the procedure:
From one of the inventors, Moore, comes a plain HTML based (step-by-step) explanation of the algorithm. Make sure you click the links. Note the following quote from Moore and think about it when watching the example:
Our algorithm has the peculiar property that, roughly speaking, the longer the pattern is, the faster the algorithm goes.
A rather neat explanation is hosted on a German site with a (Java- based, so might take some time loading) animation of the algorithm.