oh.
the reason i am asking whether are they all with .WMV extension
is to make sure they are.
to double check, i always go to "Folder and Search Options" >
"View Tab" > Uncheck "Hide extensions for known file types"
see whether one of those clips will work by changing the
extension from .WMV to let's say ".MOV" or ".RAM" or ".AVI" or
".MPG" in case the extension was indeed named wrongly in the
first place