The image seems to be locked, but at some point I wondered the same thing about a little critter in my shrimp tank. they look like little shrimp but brownish and greenish and a dart around really quickly into the substrate and burrow themselves in and if this is the case I'm 99% positive it is a scud.
The mp4 video will download when you click on the image in the post, you can then open the download folder and view it (assuming you have a mp4 video player app loaded and associated with *.mp4 filetype)
That's a seed shrimp, or ostracod. Filter feeder and completely harmless, but can breed out of control if overfed, like many inverts. I like having them in my tank, personally.
It doesn't look like any sort of fish parasite so it's probably just an aquatic critter that wanders around the bottom picking up food. If you see it attached to the fish then it could be a fish lice but at this stage, I wouldn't worry too much about it. Just another thing trying to survive in the tank.