What breed? *Picture heavy*

Watching the video makes me definitely see the border collie he just got the short fur of the staffy. the fact that he doesn't have a distinct stop in his nose would be from the bordercollie and the way he runs I see the mix lol you could always have a DNA test done

I see AM Staff in him for sure. Not all Am Staffs are short and bulky.

My parents used to show am staffs and they raised and owned a blue ribbon champion and I can say with very very high confidence that your dog is almost full American Staffordshire Terrior. Staffie Bulls are very very small, but look fairly similar. Their noses are shorter and they have fatter heads, and am staffs are basically really bulky PBTs. That's how they're seen in America anyways.