Hey Gestalt,
As far as licensing goes unless you composed and played the music yourself or the music is more than 50 years old you will need to get permission from the original composer or copyright owner.
For pretty much all commercial music this means paying big bucks.
You can choose to ignore this and use the music anyway. Given that only a small number of people will actually look at your small little windsurf video the risk of litigation is probably small.
However, if the big record companies in the US decide to take YouTube to court I think YouTube will try to deflect blame onto users. This has happened with other companies like Napster in the past. Since it clearly states in YouTubes license agreements (which every uploader signed) that you must be the copyright holder of all works the stone will sit with you in the end.
If you are promoting any products in your video you will also expose the company promoted.
My personal opinion is split on this subject. On one hand I believe this could be a great promotional platform for unknown bands. On the other hand I wouldn't really like it if my music would suddenly pop up promoting something I don't morally believe in... my 5 cents.
PS: for more info on Australian copyright legislation see:
www.copyright.org.au/