First of all- i wish EVERY customer would provide us with videos exactly like this. It makes our job so much easier!
With that said- you are showing zero volts in Live Voltage during the cut and that is the reason that you are getting the arc voltage lost error. The THC is not sensing any voltage (which is incorrect because there is voltage as evidenced by the arc being on) and that is why its throwing the error.
The good news that its likely going to be a very easy fix. Based on the fact that you get a small blip of voltage after the arc shuts off, I am guessing that you have the polarity of your arc voltage leads reversed. How is your plasma cutter wired?
If its not that, it will be something simple. Here is a troubleshooting guide that we put together for this exact issue: LS-THC Arc Voltage Troubleshooting Guide
Some other simple things: make sure you don’t have electrical continuity between the USB shell (part that pokes out of the electronics enclosure) and the slat bed both with and without the USB cable connected. If running on a battery charger, make sure to use a 3-2 prong adapter if your charger has a third prong.