Sanjuro, I take umbrance! That is not a 'typical' demo, that is an 'exceptional' demo!
I can just say, I've pushed people on the street like that twice. Once at a massive outdoor event and the aggressive jerk was on my nerves and I really had to get him out of my space, the other time, a guy was in my face - and I just removed him for both our safety.
Both times I could feel their rib cage compress and hear the wheeze and see the 'bug eye', both times they went down, both times they got up and went away... granted, sprouting foul language...
It just took the fight out of them, so, hey, I'm counting that...
To me, the single most significant issue is the telegraph, or rather lack. Going from stop to go without any twitch, breath or positioning. If you can do that, you can make Hakka boxing work.
Oh yea, Fung ahn on the end of it helps.
Guangzhou Pak Mei Kung Fu School, Sydney Australia,
Sifu Leung, Yuk Seng
Established 1989, Glebe Australia