I was tracking and demonstrating via cell phone recording through an eyepiece in my omni v rated night vision goggles how people are able to spot ufo in the night sky, and what they should generally look like in comparison to regular commercial jet aircraft such as those with faa safety lights blinking. using the goggles suspended from a helmet mount, i extended the bracket out to allow for my cell phone to record through the eyepiece and had a 3x optical lens on the front of it. while trailing an object that appeared below it, off to the top left side of the video a triangle craft emerges and brightly illuminates; which i was unaware of until after playing back the recording. i've spotted a similar shape and size triangle ufo in 2012 and reported it in a mufon report around 2018 when i was reporting on some sighting and experiences i had in 2014-2015. it was in a similar location to where i was observing from, in addition to finding other people's video recordings they made not far from me, of a similar craft (when not looking through night vision it showed up like a vantablack surface triangle object with three "lights" which could be referred to as propulsion systems. how in this video the triangle enlarges (whether it be some kind of unusual descent or some kind of holographic projection used to show itself, i have no idea. i had actually been noticing strange "flashes of lights," and for all, i know this could be when the craft launches off into some other direction, or it was merely making its presence known (which i could go into further details though doubt it would be believable.