Hi Chrysaor,
May i know what are you trying to capture, is it a swf (flash), video, video from websites, etc?
I've personally over come alot of software when i tries to capture the video on my screen, i can tell you with confident they all dont work well, because the FPS (frame per second) of your monitor is different compared to NTSC(29.90) and PAL (25fps) mode, and it's flash the fps it's even more dynamic.
I know there's a great screencapture for mac,
http://www.ambrosiasw.com/utilities/snapzprox/If you're running on pc, i would recommand you to use the video convertible software to convert the video into AVI or MPEG format.
http://www.softpedia.com/get/Multimedia/Video/Encoders-Converter-DIVX-Related/Video-Convert-Master.shtml