You should add closed captions to videos if you would like to be more inclusive. Since not everyone can hear the audio, the text will allow the deaf and hard of hearing to understand the message. It is a simple way to increase the reach of the videos.
The text generated could also serve as a tool for search engines to analyze the content. It will be easier to determine the relevant keywords and offer the video as part of the results. This should help the content creator to get a bigger audience in an organic manner.
Transcripts can be generated manually or automatically. Manual means are generally slower and more expensive but they are also more accurate. Automation speeds up the process which is great if you want to process a big archive. It also costs less per minute.