Very common in my past having shot footage of different computer screens (Dell LCDs, iMacs, iPads) with my Canon DSLR, and getting these moving squiggly lines on the screen. I've tried adjusting the shutter speed on my 5D/7D one click at a time with the dial (have gone to both extreme ends.. lowest to high shutter speeds) in live view mode, with only very minimal improvement, if any at all. And it gets better or worse depending on angle sometimes.
I've attached an image to illustrate what I mean.
I shoot computer screens often in my line of work, and need to find a fix for this. Does anyone know what I can do? It's pretty noticeable in a lot of the shots, a lot more noticeable than this image too.
A screen capture utility is the only way to get it perfect. I use Camtasia, and am very happy with it. The only way to defeat moire in camera is by slightly defocusing the shot, which pretty much defeats what you're trying to do - get a clear, clean, capture of the screen.