A loose connection could have caused issues.
How and where were the meter leads connected to the electrical system in your video. The meter certainly was jumping around. You may want to test without video to see what the voltage is. I did see it popping up to a little over 14, so if it is staying in that range, that should be good.
I'm wondering if the ammeter is off or if you really are pumping out as much current as it's reading. It's not a precision gauge, but that looked to be around 20A, maybe more.
I would expect to see that if there are a lot of loads on the battery side of the ammeter (I'm still curious about that red wire.), or a battery that is going south or had been greatly discharged. You may want to put the battery on a charger for a few hours and pull the fuse on the red wire. Then see if the ammeter is still reading like that.