Google ensures that this can be done with Drive instead of forcing people to use YouTube instead. So, the question is, how can we add captions to a Google Drive video with relative ease?

To add videos to a Google Docs document, you can insert a video via a link, add videos from Google Slides or insert a YouTube video into Google Docs.

If the video you need is stored in your Google Drive, it’s just as easy to add it to a slide. 1) As with the YouTube instructions, select Insert > Video on the appropriate slide.