One of the most features required for JW Player 7 for WordPress, was the possibility to load subtitles, since the tool for writing captions, introduced with the version 1.3.3, is not for who needs to translate an entire movie for example.

How to load subtitles in JW Player 7 for WordPress – Premium

The new JW Player 7 for WordPress – Premium 1.4.0, fills this gap with a new easy to use tool that lets you add as many translations as you need, by loading files in vtt, srt and dfxp format.
This action adds the cc button to the player, useful for the user for switching from a language to another.
This video show you how it works.