this'd be a great thing to have in a plugin
specify which dot is dead (possibly in an ini file or something similar) and the plugin interpolates around it while ignoring the rest of the video. should be really fast because only a few pixels are processed, and everything else is just copied.
one thing that concerns me slightly - ringing in the DV codec. even if the white pixel is fixed there'll still be the mosquito noise that it caused surrounding it. i think a filter could even handle this if it's clever enough and DV specific (there'll be a fair idea about where the mosqiuto noise will occur seeing as the pixel never moves).