Just copy the embed code from YouTube or other platforms, and paste it in the markdown file.
---title: Include Video in the Postpublished: 2023-10-19// ...---
<iframe width="100%" height="468" soak-rename="https://www.youtube.com/embed/5gIf0_xpFPI?si=N1WTorLKL0uwLsU_" title="YouTube video player" frameborder="0" allowfullscreen></iframe>