An exposure sheet is essentially a spreadsheet to give instructions to the camera operator on how the animation should be shot. Traditionally there are five columns with each cell being used for a different portion of the animation process. For example, there are sections for sounds and camera moves. The horizontal lines represent single frames
With the nature of Brickfilms, exposure sheets are not widely used. Another reason for this is because computer software has taken the place of exposure sheets. In addition, many Brickfilm makers choose not to have the characters mouths move, and therefore keeping track of every frames audio is unnecessary.
More information on exposure sheets: