This is my first post here so hello fellow 50D owners and ML users 
I think (this is untested as I haven't encountered the problem
) a relatively simple POST production 'fix' for the dead pixel issue, if you have Adobe After Effects, would be to use the clone tool to have the dead pixel area replicate the area on one side of it. This isn't a true fix but may help mask the problem somewhat.
Though this would become very labour intensive if the dot is moving, it wouldn't prove difficult if the dot is stationary in the frame.
I think (this is untested as I haven't encountered the problem
) a relatively simple POST production 'fix' for the dead pixel issue, if you have Adobe After Effects, would be to use the clone tool to have the dead pixel area replicate the area on one side of it. This isn't a true fix but may help mask the problem somewhat. Though this would become very labour intensive if the dot is moving, it wouldn't prove difficult if the dot is stationary in the frame.