Just start speaking. The surrealism would be amazing. Just tell them there's clearly something wrong with Zoom. Everyone will buy it.

Also, it's just yet another reason that I'm so happy my Zoom meetings do not require a camera feed. There's just something Orwellian to me about having to have a camera on me. Having a camera on me is my absolute nightmare regardless of the purpose of the camera.

You make sure you are wearing the same clothing as the recorded video loop. Use something like a stReamdeck to have hardware buttons that let you toggle to a live webcam. Elgato even has a foot pedal version that works great.

It's probably just me, but the video in these video calls is mostly a waste of bandwidth, I am never paying attention to the bobbing heads in the screen. My point being, I, for one, would not notice very quickly if the person speaking was just a loop of someone looking interested, I sort of want to do this myself, OBS is probably the key, when called to speak you could switch scenes to the live feed.

I did some research into using ffmpeg as a sort of live network based video router and compositor, My conclusion was that it would work. however my heart was set on actual transparent rgba video and support for that was finicky.