Thought I would start a list of these and see if anyone else was stung by them.
TiVo: Using a Tivo Series 2, or a Tivo HD, no eye strain. Using a Tivo Bolt, or Tivo mini, immediate eye strain. this is on the same television, on an identical input channel, with identical settings, even using the same input cabling.
Media Streaming: If I stream Netflix at 720p or higher resolution, instant eye strain. If I force it to non HD mode via bandwidth restrictions, no eye strain. Same TV and settings both times
Also, if i stream to my Tivo from a home media server, instant eye strain. Watch any other content on the same Tivo, no eye strain. Identical settings all the way around
Motorola Triumph smartphone: Original one I bought, no eye strain. I bought a replacement, immediate eye strain. I disassembled both devices, swapped the screens, turned on the phone with the screen from the device that never bothered me, immediate eye strain.
Dell 21' Widescreen monitor: I have one hooked up to a, nVidia GTX video card, no real problems. Plugged into a, HP Smartbook, instant eye strain. Identical monitors, identical settings, sitting right next to each other on the same desk
Amazon Fire Stick: Plug into a TV that gives me zero problems, instant eye strain. Same settings, same port, no changes to the TV at all. Just the driver the stick uses
Roku stick: Same as Fire stick. Used on TV that caused zero problems, instant eye strain, identical settings on TV
So it is quite apparent that every display has the capacity to cause eye strain, but only certain video drivers enable that behavior in the display
I emailed contacts at every one of these companies, and never got a response other than "Sorry". I haven't done a ton of PWM testing as to date on these devices, but I know not all of them are LED (the TV is plasma and my laptop is CCFL)