You must be logged into the Video Portal in order to request subtitles for any media content.
Simply click on the options button beneath the video, select the ‘Request subtitles’ option and complete the steps.
Please note, it can take up to 24 hours for subtitles to become available for a video due to the different services involved, and you will not receive a notification – the subtitle icon will simply appear on the player controls when they are ready.
More information can be found on the Subtitles page.