Welcome haylie182,
This is something we can definitely assist you with, thanks for posting here.
We want to help you listen to that lecture seamlessly on your AirPods. Based on what you described, we're not sure exactly what you're experiencing. With that in mind, we want to recommend some troubleshooting steps that we hope will get things working better for you. You can find those steps below:
Lastly, you mentioned Spatial Audio but we're not sure if you wanted to enable that feature or disable it. This article has more information pertaining to Spatial Audio on your Mac, so we hope it will be useful: Use or turn on Spatial Audio for AirPods and Beats - Apple Support
We hope this information is helpful!
Have a great day.