I am unclear what you are asking for.
Your screenshot is showing a Direct Play situation – no transcode.
This is the ideal case where the full quality of the file is reaching the playback device.
It doesn’t get any better.
I know that the video playback is being ‘direct’. But the subtitle is enabled.
It was supposed to be transcodeing, because Plex says it is impossible to watch a subtitled movie without a transcode.
Why in this case, is the transcode not occurring?
The Plex has a video converter. Does he also have a tool where it is possible (to record subtitles in the video)? That way he wouldn’t transcode, as the subtitled would be part of the video.
This is totally depending on both the format of the subtitle and the type of plex client.
Some clients can show you the subtitle without requiring transcoding.
If the customer accesses via a phone (a mobile-optimized version), is it possible to transcode? I don’t know if phones are capable of playing subtitles without a transcode…