That's why the video basically happens in only one dimension instead of two.
Much nicer! Very cool demo!
Super cool mesmerizing effect.
Probably not as nice as this demo, but I'm sure there must be some signal combinations that yield interesting results.
For sending a VGA signal even at 640x480 you will need a short h sync pulse of 3.8us at 31.x kHz. You would need an audio interface without filters with single low pulses at 260 kHz samplerate. Otherwise the monitor will just not detect a signal.
You could however use h sync and v sync from the VGA output and feed audio to the rgb channels. But thiswould give a mess of wires and is far from the beautiful idea shown here to just connect the white/yellow plugs differently.