Very well done!
The image in question is a photo of me and horse with a fenceline and paddock and some trees in the background. Most tools get confused with the colours in the foreground and the fence and sky colours.
MultiMatte is open source, so you can also run the model locally or in your VM too
the model does come with bounding box capability but we did not optimize for it in this release. In the next releases we intend to tackle that along with video capabilities and some other features.