Help needed to configure Movie viewer plugin to play videos

That's right. Essentially what I suggested in Is there WebM support? - #5 by Leo :

That's the method I use and it works. But it also depends on the file types you're trying to play being correct in the registry.

(FWIW, we will be making a new Movie plugin that should make things easier in the future, although the old one can still be made to work with the right 64-bit codecs and splitters.)