Does this work with all monitors?

No, some monitors - like those the flatscreen on laptops - don't even have scan lines. Those that do have different setups scanning at different rates. This is sometimes called the "Refresh Rate".

The faster the scan (usually on bigger monitors), the less likely it is that your normal eye movements will be able to distort the image.

So, the faster the scan, the less jittery the image, and the less eye strain it causes.

Experts only

You can change the refresh rate on your own computer, just be careful because doing so can be quite tricky.

On a Windows-based machine, right-click on your desktop, choose "Properties", then select the "Settings" tab and press the "Advanced" button. You should see a menu called "Refresh Rates". Write down the number. Once you've written it down, you can make the the number on the computer lower and slow the scan lines.

On a Macintosh, go to the "Apple" menu, move to the "Control Panel", and select "Monitor". Write down the number. Once you've written it down, changing the "Resolution" to a lower number will slow the scan lines.

To change it back, just follow the above steps again but change the number back to the orignal one.