For those in need of getting their Twonky Media server talking to
their Samsung B650 series tv (e.g. LE37B650) without lots of format
issues:

find your clients.db file in your twonky setup and find the "Generic
DLNA 1.5" device.

Edit it to show the following:

Note - ID number should be whatever your current "Generic DLNA 1.5"
entry is set to.

ID:049
NA:Generic DLNA 1.5
HH:DLNADOC/1.50
HP:chunked
XM:DLNA15
XM:DATETIME
DB:FIX
DL:MP4DLNA
MT:avi,divx video/x-divx
MT:mp4 video/MP4V-ES
MT:mkv video/MP4V-ES
MT:mpeg,mpeg2,vdr,spts,tp,ts,avi,divx video/mpeg