This page has been quickly thrown together in order to provide a place for screenshots and video examples. I, for one, almost never download unfamiliar GUI-based programs which do not provide screenshots. With this fact in mind, I thought it might behoove me to post some examples of the plugin interface and output. If you find yourself interested in downloading this plugin, please visit the SourceForge.net project page at:
http://sourceforge.net/projects/diffkey/

Most of the shots below show the interface from an older CVS version, which has an unimplemented "Add Frame" button. The interface is in transition right now, please excuse the ugliness :)

Once a key frame has been acquired (currently it must always be the first video frame in the timeline) you can use the sliders to adjust how sensitive DiffKey is to differences in Hue, Saturation, Value, Red, Green, and Blue - relative to the colors in the key frame.  Once having adjusted these sliders to their optimum settings, you can boost the alpha channel for the entire mask by adjusting the visibility threshold, and adjust the transparency threshold to remove faint background noise. The Desaturation threshold cancels out the background color from the partially transparent pixels. This can be useful if motion blur is causing background colors to show through. The resulting dark blur is still less than ideal, but it's far less objectionable than having blue streaks chase your subject around the screen.