Periodically oscillating chemical reactions?
A couple of points:

The demo is probably an oscillating chemical reaction, in which the concentration of a given species increases and decreases repeatedly over time. However, the energy of the overall system is dissipating as that is happening - not oscillating.

Resonance, on the other hand, is a (widely misunderstood) concept that applies to a single chemical species and not a bulk reaction mixture. Resonance does not consist of energy flowing back and forth between two chemical states, but rather is meant to represent a single energy state that is a hybrid between two (or more) classical Lewis structures. A double headed arrow between the two classical structures indicates resonance stabilization — mostly resulting from delocalization of electrons relative to the classical structures. The double headed arrow does not indicate oscillation between those two structures.