Why do videos, displayed on my LCD monitor, then reflected from the OLED screen on my phone on my desk, appear jittery?

Try this for yourself. If you have a phone with an OLED display, place it face up on your desk in front of your monitor. Now play a smooth video on your computer monitor. Look at the reflection of the video on your OLED screen (which is turned off of course) and you'll notice that the video seems choppy.

I'm not sure if this applies to phones with LCD screens or not, as the viewing angle isn't as good on my old phone.

Thanks, scientists!