Hard to tell from your video, but is the mouse input being fed into the Amiga side, or is the bridgeboard trying to do some conversation on it and feed it to the PC side? In other words, if you hook a second monitor up to it, one on the PC side and one on the Amiga side, and you move the mouse around, does the pointer move on the Amiga screen or the PC screen?
Edit: have you tried the software from here?
http://amiga.resource.cx/exp/goldengate
