AlphaPhoenix is the channel of Brian Haidet, who makes physics videos built around home-made apparatus. In this 28-minute video from November 2024 he rebuilds a wave machine from thirteen years earlier and films it with a high-speed camera, with the specific aim of showing how a standing wave forms rather than just what one looks like once it exists.
The key sections are the single-pulse footage, where you see one wave travel, reflect and return in time to be reinforced, and the section on why resonance is so sensitive to timing. There is also a detour into the MythBusters attempt at Tesla's earthquake machine and why energy accounting explains its failure. The description carries chapter timestamps.
For anyone tuning a plate or a vessel this is the missing piece: resonance is a build-up over many cycles, and the transient matters, especially when you drive with music rather than a steady tone.