Bigbulls is right...didn't watch the videos but explanation was right on.

Form is another thing that is very important. The arm that's gripping the bow should not be parallel to your chest. Your grip arm should be ~45° angle to our chest. If your draw length is too long, natural tendency is to overcompensate by making your arm more parallel to your chest to make up for it. This is one of the main reasons why people slap their arm with the string. By creating the Grip Arm/Chest/Bow String triangle, you'll eliminate a lot of these problems....because your string isn't traveling right alongside your arm.