I've had the same problem since I first installed Gizmo.
I had the same problem under MC 15, but now I'm running Media Center 16.0.179. I also have Gizmo version 16.0.179 installed.
On the PC running MC16, I have many .avi files which were imported into MC16, which I can play from within MC16 as well as from Gizmo on my Asus Transformer Android Tablet.
I also have a directory of ripped DVDs which are in the form of a directory containing a single VIDEO_TS sub-directory, which in turn contains a Video_TS.IFO file and the remaining files that make up the DVD.
I asked MC16 to import the content from the DVD directory, and it successfully found all those DVDs and added them to the Video Tab. Further, if I select Video / Files under MC16, an entry shows up for each DVD and if I select it, the DVD starts playing with both video and audio.
When I use Gizmo to connect to MC16 from my Android Tablet and select Videos, I see the same list of Video content. However, when I select a DVD, the screen shifts to playback mode, then I get an error:
Video not found:
http://192.168.0.9:52199/WebPlay/MCWS/v1/File/GetFile.flv&File=25731&Conversion=26&Start=&Token=GgikeVbwSo, what's the story? Gizmo and MC16 are not working together.