Yippee! Ellen McHenry's Cells.
Chapter 1: How did we find out about cells?
Here's the video for the workshop: Lens on Leeuwenhoek. For Hooke, Brown, and Schwann and Schleiden's Cell Theory, try this video. It's very accessible.
Other videos which may be of use: Discovery of cells. Four laws of living organisms. Cell rap.
Ellen recommends this video on SEM technology; and this video for TEM technology.
On magnification and scale in general, Ditta recommends the classic short film Powers of Ten (1968) by Charles and Ray Eames, and the game Scale of the Universe.