Ah, that explains why I didn't see it on xbmc.org :-)
No, reading that thread I don't agree with the responses - to say that "subtitles... are generally not recorded" isn't the case if you're using a .ts container, my experience is thateverything gets recorded - that's the point of the .ts (Transport Stream). The easiest way is open the file in VLC or mediainfo - both will tell you the different streams, including all audio (e.g. DEU for German and NAR for audio description) and the subtitles.
They don't come from teletext, however, since (assuming I remember my ancient history :-) ) that's an analogue signal that was embedded in the lines our TVs didn't used to display (e.g. 640 broadcast, 625 displayed). They're actually part of the DVB standard, so appear as DVB subtitles in the broadcast stream, e.g.
