If I had to guess, and I'm going out on a limb here, I'd say the difference is oohh, about 20 pounds.
No but seriously, just make sure your bag comes as a "soft fill", otherwise stuff it your self. Dont take too much from the pacman video as you dont know how old the bag is and how loosened up it has become. He also hit like a tank, so he'll bend just about any bag out there.
What weight are you by the way? A 50 pound bag is extremely light.
I do have a TKO bag that around 65lbs thats a similar plush target. But almost every bag I use is 100lb + because I prefer it not to swing as much.