Video is the heaviest thing most of us ever attach: screen recordings, camera clips, whole talks. It was born in wherever your camera, screen recorder or download came from, and its real weak spot is nothing inherently; every container brings its own quirks.
WMV is a time capsule from the Windows XP years: tidy little files with dated manners. Windows Media Video, usually inside an ASF container; once the backbone of DRM movie rentals. That makes it the right destination when what you need is old Windows archives and PowerPoint decks that still insist on it.