I’m sorry, but, respectfully, I have to disagree.
@ 0:04 dog is clearly in play - on the other side of the coffee table, waging his tail
@ 0:08 “attack” stops right at the initial engagement - angry dog/abused dog? I don’t see it.
@ 0:12 dog goes from relaxed to engaged and back again, but only “attacks” the finger and drops back out of play again - this finger is clearly being presented as a "play item”.
I had a chihuahua mut (chihuahua plus mystery component X) for sixteen years and she behaved similarly – had a very snarly play mode (snarling like this dog she would place her mouth in my hand and I would open/close her mouth and it would sound like a demon saying “ma ma” – I regret not capturing that on video…
)…
Another member of that pack (Aussie Shephard + Rottweiler mix) has two “triggers” which turn him to play mode - which is distinguished by & much more so in his youth - ferocious growling and barking: (1) placing a hand on top of his head & pressing down (a game he used to play with anyone – with Alpha approval) and (2) presenting at him with “karate” hands (this is only for me) - as both are indicators to engage in “play” as in my house we are a pack, and pack play can appear aggressive to an outsider.
I will also sometimes wear gloves and a padded forearm for “highly aggressive play” where he has more leeway with his bite – and he knows that, and gets excited when I take the gloves out. He also knows the “you’re biting me too hard" command and will immediately release into submission. Yet, at the same time, he will also get quite surely and call BS! 
when I use that command if he knows he hasn’t been biting too hard.
He’s now a grandpa and a member of a new pack (the current one), while he will engage a stranger on command he has also passed his service animal test. When I first got sick I up-trained him so he could help me out – yet he still loves that karate hands are an invitation to play rough. Yet only my “karate hands” solicit this response from him.
FYI: For quite some time now (both of the above included) I’ve only adopted dogs which would have otherwise been put down for “socialization issues” ie: they cannot go to “normal” homes because of issues they had with their initial development and/or temperament. I rescue lost causes – and I’m happy to say they thrive.
To be clear, I don’t disagree that even small dogs can be dangerous - but to say it isn’t “cute or funny” isn’t quite accurate either. Per your “qualifications” you should well know that dogs are as much individuals as we are, so neither of us actually knows what’s going on - it’s all best guess.
