It looks to me like just the same footage of him sparring with O'Brien. Edit: Actually, it is different.
So was Benny. And thought more of. There are reasons Benny was considered pd fr pd greatest until Robinson and Greb was never mentioned. Only films would show why. So Harry benefits from the lack thereof.
I cant say I found it .. just saw what someone else came across .. still , it appears to be new relative to the previous Greg training/O'Brien footage ..
There was a great thread on here years ago exploring how Greb’s reputation/estimation skyrocketed long after he fought his last fight. He was regarded highly in his day but not as some otherworldly GOAT force. Then he, gradually or rather suddenly (depending on your point of view of what constitutes suddenly over a period of decades), began to rise toward the very top. A certain Greb author/fanboi insists that the entire world press conspired against him to make it like he wasn’t good because he didn’t pay them off (which supposes, among other things, that every single highly-regarded fighter from past eras took a large percentage of his purses and distributed that money across the newspapermen who covered fights). There may be a grain of truth to that but there’s got to be more.