Ernest Rutherford's famous gold foil experiment involves the scattering of alpha particles as they pass through a thin gold foil. It led to a better understanding of the structure of atoms. It's also known as the Geiger--Marsden experiment, after Hans Geiger and Ernest Marsden who performed it under Rutherford's supervision.
Particle physicist Bruce Kennedy explains with this modern re-creation.
Other Backstage Science videos
The title says it all: this blog features physics videos found everywhere on the web: animations, demonstrations, lectures, documentaries.