You can get subtitles if the movie file has them embedded, otherwise there will be no way to view them. Check out this link for a list of supported file types:
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Thank you for response.
I was afraid this is the case, and I think it's a shame that SlingCatcher does not read the external subtitles. It may be wonderful if this feature would be added by the next firmware update
So far, when I need to see a movie with subtitles, I connect the USB stick to my DVD player; but I wished I could use the SlingCatcher instead, to take full advantage of those great network capabilities.