SamyGO

Servii`s approach for giving you Covers instead of an actual video screenshot
is more different then the original implementation by Samsung.

See it this way,
Servii says your TV what to show as thumbnail, seems to be a feature of DLNA.
Your TV on other hand chooses for it self to show the thumbnail from the video file.

First choice for infos regarding yo?r TV, and how to hack it (if possible) should be the Wiki

witch TV and firmware do you have?
if it`s an older firmware you can use the samygo tools from game menu (if available on your tv) for mounting.
if it`s an new FW, look here

but to use this approach described here, you need an patched firmware with telnet.
i think there is somewhere on this forum an telnet enabler app, witch could be enough.