I have this problem too, with WMV files. I have a rather new installation of DOpus 9.0.0.9 so all my plugin settings are default.
Specifically, WMV files are configured to be viewed by the Movie plugin. Yet when I try viewing WMV files, I get a view of either the raw content of the files, or a hex view. These files play fine not only in Windows Media Player, but in other players as well, and also in XYplorer.
My MultiView plugin was unchecked by default upon installing DOpus. When I selected MultiView and clicked Configure, I saw the Viewer DLLs could not be located message. I went to this post after seeing it referenced in another thread, but that post seems to imply that MultiView obviates... Something else. I downloaded pdqvp.dll anyway, but even when I try pointing to it in the MultiView plugin configuration, the OK button does not become enabled.
Does the MultiView plugin ever work? Why is it there at all? Why don't these WMV files play by the Movie or MultiView plugins?