You can upload the video to YouTube. After it's done processing, go to its settings. Select the CC/subtitle tab and click on the blue box (automatic subtitles). Automatic subtitles don't generate right away after upload, you may need to give it some extra time . There should be a green dot present on the box when ready Click on the download box and select .srt (as far as I know, it doesn't work on safari, but it works on chrome). .srt gives each subtitle and it's time placement (example. "3.04 - 3.08. sentence goes here") to get rid of those codes. Look up online .srt to .txt websites. A website will do the conversions for you.
You can also use it to insert links and images to a PDF file. And if you are able to add images to PDF files, you can use it to insert an image on the page that the PDF document. And if you are able to embed YouTube videos for your HTML PDF files, I can use it to add YouTube video links to PDF files. And you can use it to add audio and video to an HTML PDF file, even if the PDF file already is an HTML file. And if you are sure that you can embed the embedded YouTube video links on your own site, I can help you out with that as well. So, if you are not sure how to use it if you already have HTML files already, there are no extra fees. If not, then there are no extra fees at all. Now let me show you.