As for the question of what I know about yowies I have researched the phenomena, off and on, for 2 years. I started by getting sucked in by local historical clippings, met a lot of people along the way and found the modern happenings quite fascinating. There is more to the story than we currently know. Maybe someone with the appropriate scientific qualifications should look into that.
The researcher mentioned in the video: http://www.youtube.com/user/TheRusty222
Prepare for an interesting few hours.