Frequently asked questions - Writer
From The Document Foundation Wiki
How do I insert a sound file or a video in a text?
- select the ▸ ▸ menu;
- select the movie or sound file; and
- click on Open.
If the file-format is not recognized by LibreOffice, a message will be displayed and the file is not inserted.
A toolbar appears at the bottom of the workspace to play the sound or the video file.