I am not familiar with Spark's capabilities but the one on video did "the flip". Can Spark do that?
I totally disagree with you. "Aerial photography" which is main usage for Mavics is entirely different breed. "Free style" or "Racing" or even "Sport mode" is something that needs designated area. Parks full of people with kids in strollers shall not be even considered as such place. With respect to operator's proficiency, this buzzer (1:39) was definitely not more than 20 - 30 feet away from you and that to my knowledge is illegal. Serious pilots in real "birds" don't even think about buzzing close to or over crowd, houses etc. What would be the purpose of that?! Scare them, make them "WOW" the recklessness... If operator wants to practice or show off like Red Bull pilots, city parks are not places for that kind activities. Unless there is an official event (competition or show) organized, controled and secured by authorities.
This careless behavior documented on the video kills this small bit of tolerance that we try to build operating "Photo Drones"... Just my 2 cents...