It is intended to be multi-language. There are two files that you need to use in the OBS directory:
locale/en.txt
plugins/DShowPlugin/en.txt
To translate to spanish, in the files translate the text on the right part in quotes, and then save the files as es.txt instead of en.txt. Then you can open up the program and spanish will become selectable, and your translations will appear, and you can check to make sure everything looks right.
Just translating and adding the files is all you need to do, the program detects the new files and adds the language accordingly. Paste or send me the files after you're complete and I'll add them to the binaries/installer.