Edit 2023 videos into prettier form

[jducoeur]

The current videos are raw and unprocessed -- they include all of the SpatialChat chrome, include a few seconds of futzing with controls at the beginning and end, and so on.

In a perfect world, these would be prettier, with somebody editing out the unneeded seconds and cropping the view.

The current situation is "good enough", so this is low priority. But if somebody is motivated, we might want to edit and re-upload them.