Flying the Flag - But which one?

This video addresses the history of Australian flags and the executive and legislative power to 'appoint' a national flag. It discusses whether the requirement that the Australian National Flag be only changed with the approval of a vote of the people, is legally effective, or just a political imperative. It notes that other flags can be altered or revoked as Australian flags by an executive proclamation.
In the wake of criticism by the Opposition Leader of the use of Aboriginal and Torres Strait Islander flags behind the Prime Minister during press conferences, it also addresses whether there are any rules about which flags should be used.
COMMENTS: Sadly, I have turned the comments section off, as there were too many comments that were racist or abusive in nature. It hadn't occurred to me that a video about flags, their history and the Constitution would produce such vitriol. Apologies to those who wrote insightful and constructive comments, which have now disappeared. And my apologies also for my mispronunciation of 'ensign'. I am clearly no vexillologist.