Hans Jenny was a Swiss physician who coined the term cymatics in the 1960s and filmed his experiments driving powders, pastes and liquids with sound. This upload is the first of three parts of that original footage, posted by a third-party channel in 2012; the description says the films are available together on a DVD titled Cymatic SoundScapes from cymaticsource.com.
The footage itself is the point. You can see the tonoscope and plate work that everything since has copied, and the material behaviour, particularly of viscous pastes, is still hard to reproduce well. Jenny's commentary tends towards the philosophical, and his later followers have drawn much more from it than the experiments themselves support, so keep the pictures and treat the interpretation as a period piece.
Be aware this is not an official archive channel. The video quality is what you would expect from film transferred to DVD and then to YouTube.