I was in the yard of an old place of residence. One of the squirrels happened to have made its legs useless, presumably from a fall. As one can see, I recorded it trying to run from me (and failing; don't worry, I just startled it and didn't do anything to it) as I stepped out of the backyard door. What would you advise?
Probably call an animal control centre, you might be able to take care of it, but not sure if it's being partially paralyzed will require extra medications or whatnot. Likely the best thing for it would be to have it euthanized so it doesn't suffer.
Some areas have Rehabilitation Centers for wild animals, particularly mammals. If it's saveable, they'll do everything they can. Once it's healed (if it can be), they'll want to return it to your property as well.
I feel that. Poor little thing needs a little wheelchair and stair lift for it's tree.