Kangeroos and the small wallabies can be seen hopping around some streets in some towns, and it it mostly in the outer suburbs where there is still some vegetation around so they can go and eat some grass.
You wouldn't see that in major cities unless someone has any illegally and they escaped the owner's location.
Snakes, well the one in the vid looks to be tree snake and while some might bite if they frightened, for the most part they are quite friendly if you approach them quietly and they are not venomous. The ones to look out for are the red belly black which can be venomous but in actual fact are good to keep around, as they will attack and kill the more aggressive brown snakes which are highly venomous. Down in Tas we have Tiger snakes of which I haven't seen one as yet in 6 years we have been here. Up on the mainland on our old rural property, we used to have a big ol' black snake that lived under a big rock out the front, our agreement was that we wouldn't go near it and it wouldn't come near us in the house! We lived there for 21 years and both of us kept to our agreement!
The koala in the vid, I would say that it had been in one of gum trees around the house somewhere and it just decided to pop in and have a look around. They are not as cute and friendly as they look though as they have very sharp biggish claws (to climb trees) so I would have just chucked a thick blanket over the top him/her and gathered it up and taken it outside and set free near a gum tree.
LOL! the wombat........ ahh yes, my fave little animal.
They are more prevalent down in the southern part of Australia and we have them here in Tasmania. The one in the vid looks like one that has been living with humans...... some people take them in to look after them after their mother has been killed by a car and they raise them, like you would for a dog or cat, and they are either released back into the wild or are kept as a pet but I think you have to get special permission to do the latter.
So yeah, while we have some dangerous little critters, I would much rather deal with one of the above than meet a big ol' grizzy bear while going for walk in the woods on summer's day!!