I found this site via the previous post. Here are a bunch of instructional videos on the broadsword from the Cateran Society in Portland, Maine.

Nineteenth-century Highland broadsword master Thomas Mathewson wrote:

It is the cultivation of this art that unfetters the body, strengthens it and makes it upright; it is it that gives a becoming deportment and an easy carriage, activity and agility, grace and dignity;- it is it that opportunely awes petulance, softens and polishes savageness and rudeness, and animates a proper confidence; it is it which in teaching us to conquer ourselves, that we may be able to conquer others, imprints respect, and gives true valour, good nature and politeness; in fine, which makes a man fit for society.