Try building custom widget for your video player because Mendix Video player doesn't support this kind of action because what you are trying to do adding .srt files for video which not possible try building your own custom widget.
I Hope this will Help:)
Hi Reemali ,
The Default mendix video player widget doesn't support .srt subtitle files directly , which is why your subtitles aren't showing even after uploading the file.
Alternative, You can use:
Use a Javascript based video player like Video.js inside mendix Using Html/JS Widgets , which has better subtitle support. Just check Video.js first and try to embed 1 short video with subtitle.