Same problem here, would appreciate any help.
I did confirm that the ffmpeg path is set in ffmpeg.location, yet, in the DB cache folder, all of the files have the appendix ".unsupported".
Do I have to create a special profile to get Twonky trigger ffmpeg thumbnail creation? On a different NAS using the same Twonky version 8.4.1 the behaviour was different: there, the same thumbs were automatically being created, but it was too slow and running forever. I don't get why the same package on different hardware platform, in the default configuration, has a different behaviour. Please help!
I should note that when browsing the server thru the web UI, the same behaviour of the relevant files not having a thumb, so maybe a more general problem than with the Samsung TV?
Update.... as you can see here I resolved it by reinstalling/reconfigured.viewtopic.php?f=2&t=31469&p=67991#p67991