Adding captions and subtitles to HTML video - Developer guides | MDN
Sample MP4 Video file - Easiest Video Editor Converter
MP4 and MKS that has a PGSUB does not direct-play, but if the same MP4 and PGSUB were in MKV does. · Issue #398 · jellyfin/jellyfin-media-player · GitHub
ffmpeg - mp4 video loading forever and does not open of Samsung TV - Stack Overflow
How to Add Subtitles to MP4 on Windows & Mac
video - ffmpeg mov_text subtitle too small when converting mkv to mp4 - Video Production Stack Exchange
Sample Videos / Dummy Videos For Demo Use - YouTube