Some particularly interesting lecture-demos are not easy to set up in the classroom, or are difficult for students to see well. These videos can be useful in these situations.
Ball-and spring model of a solid, in motion. Computer animation.
Two pucks pulled by the same force, one from the center, the other with a string wrapped around it. For a theoretical analysis, see section 9.3 of Matter & Interactions 4th edition.
Observing surface charge on a high-voltage circuit. For an explanation of surface charge in circuits, see sections 18.4-18.8 and section 18.11 of Matter & Interactions 4th edition. [Video and detailed description of the demo]
Charged straw near a high-voltage circuit. A video by Hermann Haertel that shows the detection of the electric field near a high-voltage circuit (if the video does not appear, replot the page).