Slow Dance ( Time Frame ) using Espruino ( any flavor ? )

At 80Hz you could easily use Waveform and analogWrite (with forceSoft:true) - they use the same timebase so will always be properly in sync. You can output a sine wave from a table using Waveform and can then use analogWrite to output the strobe.

With the camera - I think the problem you have is that most video cameras don't use a global shutter (it's a curtain shutter) - so you're going to see 'banding' if you use a strobe light.