Robert_Charlton - 1:52 am on May 5, 2012 (gmt 0)
darkage - I'm not sure whether I'm within the posting policy of this particular forum in suggesting search terms, so I'll try to be general.
The process of adapting DVDs for release in a particular area is called "localization"... and "subtitling" is one possible component of that process. Also, "translation" generally would enter into the kind of subtitling you want done.
If you search for combinations of the above terms and their variants (eg, translation, translating, translators, etc), along with DVD or BluRay, you'll most probably identify companies, but not likely individuals, who performs these services. These are going to be harder to find.
("SRT", which you'd mentioned in your original post title, is generally too specialized a search term to use to identify the people or communities of people doing this.)
Most large cities or metro-areas with film production communities generally have "production directories", which might be further modified by words like film, video, TV, or creative, along with a placename, to locate them. You'll then need some good luck and persistence in drilling down to translation or multi-lingual services, or however they're described. It varies a lot. It's likely to be rare that you'll find individual translators listed.... most likely just companies who hire them.
I'm going to risk getting too specific for posting guidelines (but in the motion picture and TV commercial world, this is almost like saying Yahoo or Google)... and I'll mention the LA 411 Production Directory in the Los Angeles area and The Reel Directory in Northern California. There's also a 411 guide for New York. There may be other directories in Los Angeles. I'm not familiar with other cities.
Online freelance sites may also contain categories for people who are appropriate. I would not hire just any translators to do subtitles, btw, as there's quite of bit of craft and nuance involved.
Various language combinations of course may change the outlook of the above entirely.