Simply open the audio part of the video by converting it into a mp3 file.

Then open the audio file with soundforge or another mp3 editor, find the beginning of the sentence and the end through the visual mode of the audio signal.

Finally add these values into the srt file (subtitles file).

For example :

00:00:28,528 --> 00:00:31,572
The way of life can be free and beautiful.

00:00:31,657 --> 00:00:33,699
But we have lost the way.