System: Windows XP PRO SP3
Software: MandSoft Screen Movie Studio v.2.6.2
Here is what you do if you go to record a screen region or any online video with Screen Movie Studio by MandSoft and that region displays as all purple.
In my case, I was recording a Silverlight video. The fix for this and probably for other issues involving purple capture (which means no video is being detected at that site) is to install the latest update of whatever technology is being used, in this case I needed to install the latest update for Microsoft Silverlight.