As you can see from the videos, it was really into grooming. The dark feathers were more of an iridescent green. I would guess that it is a Muscovy duck. It is native to Central America and South America, although there are feral populations of these ducks which establish themselves around the globe. There are folks who breed them. This may be one that got away.
Some websites mention that these can be an invasive species.
I remember how I really enjoyed the wild turkeys five years ago, before their numbers swelled and turkey diarrhea made the sidewalks slippery. Hope that doesn't happen with these ducks. Maybe they will interbreed with the turkeys. One can only hope.