I had a similar feeling looking at the black. But I would not yet blame the horse - it did not look like the person knew how to longe the horse.
But I also think he is too long strided and free moving for a person in your situation.
The videos run really jerky on my computer, too jerky for me to tell if the horses are lame or not, but at a total guess I'd say neither the chestnut or black are lame, they're just stiff, out of work and sore footed.
I honestly doubt any of her horses would work out for you. You should not be getting anything that is not in work and being done something with.
What about looking up these horses on
www.dreamhorse.com? They aren't saying they will trade for cattle, but you'd probably make out better if you sold the cows anyhow.
Tootling Ricochet
Missy Sugar Lynx
Poco Shandy Chex
Toola
3 are in Washington, 1 is nearby in Oregon.
Toola is 12, sturdy and not too tall. She is very pretty.
Mr Shandy Chex is 11, looks sturdy, is a little taller, and the description goes into detail about how reliable and easy he is.
Just a little taller than Toola is this nice foundation Quarter Horse mare, Missy Sugar Lynx. 17 and only a few hundred dollars. She sounds just slightly peppier than Mr Shandy Chex.
Ricochet is 9 and sounds very quiet. She is really a beautiful animal and very cheap. She is not as tall as Mr Shandy Chex, she really is a very nice size.
Not having seen these horses and assuming the descriptions are fair, Mr Shandy Chex sounds like a very quiet reliable animal and confidence builder, as well as up to carrying weight.