It sounds to me like the boards were part of a group. If you just make a rectangle, then use the push/pull tool to make a board, the steps used above work. But, if the sides have been grouped (either manually or by using the shapes plugin to make the board), then you first have to double click with the arrow tool on the board to edit anything in that group. You know you did it right when you get dotted lines around your board. Once he hit explode, the board was no longer a group, but just a bunch of lines and surfaces, so that also works for making the hole. But, once it is exploded, the board can't move as a group anymore. Note, if the board is part of another group(s), you have to keep double-clicking until you get to inside the boards group.