In the beginning up to about 45 secs, it looked like as if the greyhound was correcting the pup like she wanted to keep him on the ground lol. Maybe some sort of controlling behavior there? I don't know.
Even though she kept going for his neck and gnawed on his legs, I didn't see any intensity in those bites and her ears were back and tail carriage was mid level with frequent breaks which is good. She also let go right when he made a noise at around 44 seconds which is also good.
After that she tried to initiate game of chase and ran and ran and ran and every time she ran towards she did not make contact which was good and only started a game of tagging at 1:12. After that tag, the pup lip licked a couple of times and moved away from her and then she tagged him again at 1:16 which he didn't like, but couldn't help himself and chased her. At 1:23 I think the pup was done playing and shook it off at 1:29 to signal he's done. After his shake, the greyhound took the cue nicely and did not come towards him and went off to sniff or potty and the pup at 1:37 seen her taking a break and he starts sniffing the ground to take a break too. (you can see these things better at 1/2 speed)
It's good for dogs to have breaks and interruptions especially if you feel like it's too much. There's nothing wrong in intervening and calming things down. The pup did look pretty tired though.