Huffyuv playback

[morsafr]

Recently something went wrong with my system. Now I cannot play videos encoded with certain codecs. For example Huffyuv and Cinepak are not working anymore in Windows Media Player. I have the following error: "class not registered".
But when I open those videos in VirtualDub there is no problem. So I think the issue is linked with a DirectShow playback filter.

So here is my question: does anybody know what DS filter is used to play Huffyuv videos ?

Thanks