Using a clothes dryer for heating and cooling

The title says for "free", but how does the air move from the dryer through the vents?   There's another video that shows how to make another piece to this set up.  During that video, he discloses that you have to use an electric dryer, not a gas dryer.  Therefore, it uses energy.  Glad to get that cleared up.

Would this be useful?  Maybe.  Depends upon how much electricity is being drawn by running the dryer.

Some type of ventilation may be useful, but since this is used with a dryer, it is not going to be useful unless you are drying clothes.