Making a compressed version using one subtitle stream

Using DVD Studio Pro, I've made a DVD with three subtitle streams (French, Spanish, and German). Now I need to post the German version to Vimeo. How can select that subtitle stream, and make a compressed version of the film for upload? Any help greatly appreciated.

The subtitle streams were imported to DVD Studio Pro as STL files. From what I've seen, Youtube either requires you to type in the subtitles as you go (something I'd like to avoid) or upload them as SRT files. I've found converting STL to SRT (and vice versa) extremely challenging and time-consuming, so I'd also like to avoid that option.