Need help reasoning about video oscillation >60hz
Yeah, that makes sense. Most flat panel monitors on the market have a 60Hz refresh rate! So you are not going to be able to flicker faster than 60Hz due to technical limitation.

Were you to do this with a electron sweeping oscilloscope, or a LED lamp connected to a PWM source fast enough then no problem (you can find this in arduino samples). It would work. 

You can also emulate the effect by rendering multiple frames and then blending them. But you should take careto do correct kind of blending as the monitor output is not nesseserily linear!