If it was an old beaver pond, and then later a swamp, then there could literally be almost anything in there.
However, none of the little surface pips look like they came from anything sizeable.
If they are fish, they appear to be a small species.
Anything called a "minnow" in PA that is considered invasive or undesirable?
Any invertebrates/amphibians/salamander creatures in the area that are undesirable?
I suspect once you get BG or eventually a larger predator into the pond, they will eliminate any slow-moving critters.
Also, I don't think those size of pips in the video indicate something large enough to consume your FHMs. However, I have been wrong plenty of times before!
Keep observing your new pond. Maybe someday when you have clear water you can throw in some bread crumbs and see what is hitting the surface.
Have fun developing your pond!
