Depends really on the legal jurisdiction (where you are). Ask a lawyer in your state/province/region in Australia. Some laws that you'll need to consider are privacy-related laws and violence against women-related laws.
Some jurisprudence (court decisions) allow the taking of videos if you are an established news organization or you are making a documentary involving non-hired anonymous persons or commercial film with hired actors which requires a permit from your local government. There will always be loopholes so be sure to do your research so you can use these to your advantage.
Since Australia is part of the British Commonwealth, it will likely have common laws (established laws by tradition or previous rulings or maybe even made by the House of Commons) and legislative laws (made by your congressmen and senators or House of Lords).
Likewise, if you are going to publish those in Youtube, Youtube has very specific guidelines so your videos wouldn't be taken down with valid viewer complaints.
If you are using paid models in your videos, then there really is no problem. Just let your models sign a waiver which should go hand in hand with their contractual obligation to perform as models/actors in your infield videos.
Paid models is one of the reasons why I always take infield videos with a grain of salt. But if you look at Youtube, there are videos out there that are really bordering on the illegal like brawls and street fights.
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Approach. Open. Escalate. Isolate
Here are my two essential rules on texting that will save you tons of time and money:
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