Zoom Meeting with audio from a video I am playing on my host machine

Welcome to the Zoom Community, @FRRL.

It's actually pretty easy to do this.  Start by clicking the green Share Screen button at the bottom of the Zoom window.  When the Share Screen window pops up, select the Advanced tab.  On the Advanced tab, click the Video button.  When you do, the two check boxes in the lower left will automatically be checked.

These are what enable smooth video sharing along with the audio from the video being played.

Then click the blue Share button.  A file selection dialogue box will be displayed. Navigate to select the file to be played and click Open.  You will immediately see the Zoom Video Player window:

You can click the Play icon or Pause as needed, you can adjust the volume, you can skip forward 10 seconds by clicking the Right Arrow key, etc.  When you are done playing your video, click the X in the upper right, and you will stop screen sharing.

I highly recommend playing your video in your own test meeting in advance.  And read the detailed requirements in this Zoom Support article:

https://support.zoom.us/hc/en-us/articles/360051673592-Sharing-a-recorded-video-with-sound-during-your-meeting

Good luck with your video sharing!!