I'm sure they can see a fluorescent light bulb, but it might be more flickery to them ( at least the conventional type; the little "energy saver" ones flicker at a much higher frequency ).

The illusion in question is called "persistence of vision", where human eyes don't register things that happen in less than 1/30th of a second. This figure may be different for other species, and dogs might very well see the picture being "painted" on the CRT. Just like that line you see if you try to take a picture of a TV.

However, I don't know how dogs feel about LCD or plasma.