I tested the repro-steps and found that the ZoomHelper was not listening, althou...

I tested the repro-steps and found that the ZoomHelper was not listening, although it was installed . In this case i was prompted to download zoom.pkg rather than activate video.

I'm guessing it was because I have MacOS firewall = strict (no listening ports)

Also, here's a nice tip to show all listening apps (good habit while cleaning up)

  lsof -i -s tcp:listen |awk '{print $1 " "$8" " $9}'|sort|uniq
  COMMAND NODE NAME
  Google UDP *:mdns
  SystemUIS UDP *:*
  SystemUIS UDP *:53611
  UserEvent UDP *:*
  WiFiAgent UDP *:*
  identitys UDP *:*
  rapportd TCP *:49152
  rapportd UDP *:*
  sharingd UDP *:*