Source (required if based on other people's work): https://github.com/wancharle/vlc-subtitle-explorer
Browse freely through the subtitles of a video and synchronize the caption with the paused moment in the video.
How to use:
Pause the video as you slide the caption. Browse through the list of Subtitles until you find the correct subtitle for the moment you stopped the video.
Click the Sync button to synchronize.
Wait a few seconds for the VLC to sync the caption. With bigger delays, VLC freezes during the synchronization. Then just wait, its normal.