: Search for "Flatliners 2017 YTS subtitles" on reputable subtitle sites like YTS Subs to find the specific file for the YTS.AG version.
If the subtitles are slightly ahead or behind the audio, you can fix them in real-time using VLC Media Player: subtitle Flatliners.2017.720p.BluRay.x264.[YTS.AG]
: Go to Tools > Track Synchronization to enter a specific numerical offset in seconds. Permanent Fixes : Search for "Flatliners 2017 YTS subtitles" on