Acrobat Reader is the normal windows reader.
I thinl (?) it can handle videos. Unfortunately, it cannot read DRM .pdf files.
Digital Editions can read DRM .pdf files, but can't (I think) do videos.
Maybe when you installed Digital Editions it stole the .pdf file association from Acrobat Reader?
As long as you don't apply DRM to your .pdfs, most people should be able to view them with the standard reader including videos.