Ok, well here is the standard for second degree murder:
Minn. Stat. Sec. 609.19 wrote: Intentional Murder: Whoever...causes the death of a human being with intent to effect the death of that person or another, but without premeditation; or
Unintentional Murder: Whoever...(1) causes the death of a human being, without intent to effect the death of any person, while committing or attempting to commit a felony offense other than criminal sexual conduct in the first or second degree with force or violence or a drive-by shooting; or (2) causes the death of a human being without intent to effect the death of any person, while intentionally inflicting or attempting to inflict bodily harm upon the victim, when the perpetrator is restrained under an order for protection and the victim is a person designated to receive protection under the order. As used in this clause, "order for protection" includes an order for protection issued under chapter 518B; a harassment restraining order issued under section 609.748; a court order setting conditions of pretrial release or conditions of a criminal sentence or juvenile court disposition; a restraining order issued in a marriage dissolution action; and any order issued by a court of another state or of the United States that is similar to any of these orders.
Well, intent here will be difficult to show, as you would need evidence showing that the goal was to kill Floyd, which will be really, really hard to get. We all saw the video, and while we can make an assumption that was the cop's goal, he would deny such, and likely provide some counter argument that Chauvin felt that Floyd was still resisting arrest which is why the length that it was. This is different than third degree, where intent is irrelevant; for second degree you need to show intent to meet the first test.
If you instead are going for the unintentional components, you would need to show either (1.) Chauvin was committing a felony in his actions, or (2.) Chauvin performed the act with an order for protection against him (which is clearly not the case). So the only hope here is to show that Chauvin was committing a felony in the act itself, which will be even more difficult to prove-- he is a cop and assault/battery are part of the job and he does have authority to use force-- even deadly-- when he feels threatened. So you'd have to show that his use of force was entirely out of order (tough to do against a cop) and the murder resulted therefrom.
This is risky for a prosecutor. Not at all clear that these facts are met and the defense has some fair defenses to these components.
As to the aiding and abetting, I think this analysis hasn't changed, other than it still requires an intentional act to further the crime itself. That is a tough sell, because there is no evidence he intended to kill Mr. Floyd with premeditation, and he likely did not inform the other cops he intends to rough Mr. Floyd up and they assisted in that occurring.
So I don't like it. Not saying it isn't impossible, but it is not anywhere near a slam dunk. Third degree is a lot safer and more likely. Second degree is a stretch IMHO.