While .VOBs use a "streamable" codec, they aren't a recognized file type for streaming. (They probably never will be, because the entertainment industry doesn't want you to "rip" your DVDs and breaking even the relatively simple DRM on a DVD isn't legal
in many jurisdictions. But that's a different discussion, for a different day.)
You can concatenate all your .VOB files into one and rename to (IIRC) .mp2 or .mpeg to get them to stream, however.
I'm not on the WHS team, I just post a lot. :)