You can find all translation ready strings of rtMedia here -
Now, you can translate strings ( if they are not translated already ) in 2 ways.
1 . You can contribute to the translation project on WordPress.org. Once it is approved we will add newly translated strings to our next version of rtMedia.
2 . You can use your own translation. For that, you will need to use the
.po file to refer required string and generate a language specific
.mo file once you are done with the translation.
I hope this cleared your doubts.