Help with this video

 Play, Tootsie, is very, very vocal when playing also.

 You  should hear my three play! They sound like a pack of wild monkeys, fighting with dogs, LOL. They're ALL vocal dogs, and it gets very noisy. As long as the body language is loose, I don't worry about it, and even encourage it.

To me, this all looks like play. Nikon's body is very loose (from what I can see) and I do not see any tension or stiffness in the way he is holding himself. A dog who is uncomfortable in this situation would have a stiff, tense, and uncomfortable looking body posture, and probably would try not to be laying on their side. Niko's body looks relaxed, and loose. And IMO, how stiff a dog's body is extremely important in reading what they are telling other dogs/us.

Also, his snarling isn't an offensive "get the hell away" snarl. The corners of the lips are pulled back pretty far (similar to a submissive grin), and the corners of his lips are "V" shaped. His 'snarling' is more of a play-snarl/submissive grin. It doesn't have the characteristics of an "I will bite if you pester me more" snarl where the mouth is usually more closed, the corners of the lips are not pulled back but puckered up, and the corners will form a "C" shape. When giving a snarl to try and communicate annoyance or as a warning, their entire faces will be tense and wrinkled. His face seems relaxed.

Also, I do not see any direct eye contact, any staring, or any evidence of a "hard" eye.

If he were really annoyed, you would see an actual correction. He would probably have a stiffer body posture, as well. My dog plays in a similar fashion as Nikon in this video with small breed dogs. Same noises and same actions. It's vastly different from when a small dog is pestering him and he wants them to go away.