Horse is lame, I call off fore, but not enough at straight to tell for sure, but this horse is not sound.
Video bothered me too much to watch past the first couple of seconds.
Also, even with tiedown, rider has reins so taut it is wonder they don't break, and they are twisted on off side several times, which may mean rider has had to wrap around hands to stop her.
Also think this mare has been ridden very hard, or lunged to get a lot of her edge off.
But she darn sure isn't worth almost 5K, by any means.
If all you want is to pleasure ride, you can find one a lot more reasonable than this one moneywise.
Shame you aren't in OK, there are some wonderfully gently QH right now, on a feedlot that are kid safe, and around 600. They just are trying to find homes so they don't get on KB truck. Two palominos I would snap up in heartbeat, but I just do not need another horse.
Horses make me a better person.