See http://bugs.musicbrainz.org/ticket/2718 (which is a generic ticket for adding support for videos). In the comments, luks says "Well, tagging WMV or any codec in MP4 is trivial. It's just a matter of adding a couple of allowed extensions, because the tag formats are identical to the ones for audio."

This ticket then is for adding .wmv and any other extensions which would be considered trivial. I've already tagged video .mp4 files fine, so maybe nothing needs adding there (unless there are more extensions for MP4 video, .m4v perhaps?). I'm not sure about any of the other formats Picard can read, probably .ogv too?