Phillips (North Hollywood) was a firearms aficionado who was trained from childhood in the use of firearms. Muhammad (Beltway) was former military. Neither were "shlumps." Training in the context of Dallas means the shooters had coordinated ground fire, with covering fire from an elevated or hidden position (the sniper), a fallback position, a getaway vehicle and at least the fear of bombs to keep response scattered. The video of the cop getting shot shows a guy moving in a fairly tactical way, with movements to the left and right and keeping the gun steady and aimed.
This is "what the fuck it means" when somebody talks about it looks like they had some form of training. It could be they picked it up at some fantasy gun nerd camp, but my money is that somebody involved with this was former military.