1st video: It all looks like pretty normal puppy play...and it sounds like normal puppy play too.
The only thing I would watch out for is letting one pup pin another one down for too long down in the lower portion of the floor. I'd whistle or something to see if the one on top would jump off to see what the noise was. (distract him)
The pup on the bottom really has no way of getting up, he's pinned on both sides.
That's normal puppy play
You shouldn't need to interfere at this age, they're learning bite inhibition from each other. That's important if you have kids around them. When the other one cries, they should stop automatically. They learn exactly how hard they can bite before they cause pain to the other one.
If a dog doesn't learn bite inhibition, especially with a strong dog like Rottweilers, if they get scared or cornered, they could bite through your arm if they don't know how hard to bite, while a dog with good bite inhibition will just growl or nip to get you to move back if they feel threatened.
Definitely normal puppy place. Puppies learn how to bite by hurting each other. It's a bit more complicated than that, but that kind of sums it up. They bite pretty much as hard as they can when young, and when their littermates yelp, they slowly learn not to bite as hard.
If it's just two puppies fight, I wouldn't interfere, I would let them figure it out as that's what animals do. If one puppy seems to be getting bullied by more than one, then you may have to make them take a break to slow things down.