Samsung TV grotuvai nelabai draugauja su vidiniais ("įsiūtais") subtitrais.
Pagal Samsung TV Plex appso, kuris naudoja vidinį grotuvą, instrukciją, tik 
kai tam tikrais atvejais, "įsiūti" subtitrai atvaizduojami, o norint juos 
pamatyt - reikalingas perkodavimas.

Some movie formats like MKV  will allow you to add the subtitles inside the 
movie file.
These  subtitles cannot  be  accessed directly  by  the  app.  It  needs 
help  from the
Samsung API  to get these from the movie stream. If the subtitles are added 
to the
movie in  a standard way,  it is possible to retrieve  the  subtitle  and 
show them as
overlayed  subtitles.
Unfortunately  this  only  works  for  text  based  subtitle  formats.  If 
your  movie  has
VOBSUB or PGS subtitles, which are based on images instead of text, this 
option will
not work.