One of our readers, Mike, sent in this video he filmed of oscillations on a 12-string guitar. He used and iPad 2 and iPhone 4 to record it, and it's definitely worth a watch.
His trick to capturing the oscillations was simple - playing his guitar outside and in direct sunlight. The reason this works is because
the camera must adjust to the extreme light by filming with fast shutter speeds the iPhone and iPad use a rolling shutter that scans the frame vertically. It follows that the camera must be used vertically in order for the effect to be seen.
I keep coming back to this video and find it so intriguing. It helps that Mike is an excellent guitar player! I teach a College Trigonometry class, and I'll likely show this video to them as an example of sine waves in action!