Check In Thumbgen …
Options > Input / Output Naming > Movie Info Export > .xml > Export Using WDTV Live Hub format
inside the xml eg.
The Dark Knight_sheet.jpg
Moviesheets will not display for “Folders” (Linksheets however, will *but you will have to modify the mojo theme.)
More info about Linksheets: http://community.wdc.com/t5/WD-TV-Live-Streaming-Discussions/THEMING-ISSUE-FOLDER-THUMBNAILS/m-p/535195#M17305
