First off allow me to introduce myself, I am Greg’s Brother In Law and fellow budding photographer. I hope to post some useful links for you and some of my own images if I ever think they’re good enough to share! I have a lot to learn.
This link in question is to a site I’ve been watching lately run by photographers Patrick Hall (www.patrickhallphotography.com) and Lee Morris (www.rlmorris.com) called fstoppers.com They created the site in order to show high quality videos of photographers working and discussing their methods.
This video in question is by Paul Duncan and describes how flash sync works in hot shoe based DLSR flashes.
Most illuminating. Enjoy.