It seems like your denon receiver part number is missing a digit. Are you sure it's not a AVR-2312 CI or AVR-2313 CI? I didn't have any luck locating details on a Denon AVR-231 CI
I own a Denon AVR 2312-CI, but haven't used the PC media streaming features. I think I have some "homework" to play with tonight.
Edit: After digging through the manual for my AVR 2312-CI, I don't believe you can stream videos through the network. Per page 35 and 36 of the manual (found here:
http://usa.denon.com/DocumentMaster/US/AVR-2312CIE3_ENG_CD-ROM_v00.pdf), the receiver can stream audio, and images (album art, or slideshows), but makes no mention of media player video capability. Page 36 of the manual also lists the compatible media server file formats as: WMA, MP3, WAV, MPEG-4 AAC, FLAC, and JPEG (none of which are video - except JPEG for stills). The text from the manual is below for convenience.
Of course, the info above is from the manual for the AVR 2312 which may differ from yours especially if you have the newer XX13 model.
Media playerThis function lets you play music files and playlists (m3u, wpl) stored on a computer (media server)connected to this unit via a network.With this unit’s network audio playback function, connection to the server is possible using one of thetechnologies below
Windows Media Player Network Sharing Service
Windows Media DRM10
Album art function
When a WMA (Windows Media Audio), MP3 or MPEG-4 AAC file includes album art data, the album artcan be displayed while the music files are playing.If you use Ver.11 or later of Windows Media Player, the album art for WMA files can be displayed.
Slide show function
You can play back image (JPEG) files that are stored in folders on a media server and photographs on Flickras a slideshow. Also, you can set the time display that is shown during playback
page 92).This unit plays back image (JPEG) files in the orientation in which they are stored in the folder.Function that simultaneously plays back music and image files from the network
You can playback music and image files at the same time by playing back music files, and then playing
back image files.