Can not reproduce results of one item transferring from hopper to minecart with chest

In Etho's video - http://www.youtube.com/watch?v=jN-9BI2GHdU - at time 1:51 he shows how to remove one item at a time from a hopper to a minecart with chest. This works every time for him while using Snapshot 13w09a. I am using Minecraft 1.5 and I can not reproduce his results. My attempts remove two or more items at a time.