This is on my sister'* 1997 Ford Crown Victoria LX. It should be noted that the passenger front fuel injector is currently unplugged. When plugged in, there is frequent backfiring in to the intake. Unplugging the fuel injector yields 1-2 more backfires, and then it goes away. The engine is definitely not happy in it'* current condition. There was an oil change done very recently.

So, what does it sound like to y'all? Feel free to link the video to those who could help as well. This is after the engine has ran for a minute, before that it sounded like there was more of the valvetrain joining the party, than everything else got quiet, and the original issue remained. I tried pulling the valve cover, but can't get to one of the bolts right now.

Dropped valve maybe? Pull that valve cover.