I just caught a replay of Glenn Reynolds being interviewed on C-Span. For those who don’t know, Reynolds blogs as Instapundit, and was one of the pioneers of blogging. The interview ranged widely, and although primarily focussed on politics (unsurprising, given the nature of his blog), did cover some IP territory.
One of Reynolds’ perceptive comments (there are more; the whole thing is worth reading) was:

REYNOLDS: … And there are blog sites that really focus on the TV stuff, and even post video with segments that people talk about. Crooks and Liars is one which is on the left, Exposing the Left is one which is on the right. As you might imagine, they disagree a lot about their takes on different stuff. But they actually post video and people comment on it, and people go from there.
LAMB: How can they do that legally?
REYNOLDS: I don’t know, to tell you the truth, but what’s interesting is that the people whose video they post don’t seem to mind. I mean, you know, there is a plausible argument that it’s fair use, but it’s interesting to me that not only do people from the big networks not complain about that, they actually seem to like the coverage and sometimes to encourage it.

A few points:

1. The kind of fair use he mentions might be one of those narrow kinds that is also available in Australia; perhaps s.41 of the Copyright Act (fair dealing for purpose of criticism or review).

2. The practice itself shows the value of having the fair use/fair dealing defence. It’s the kind of transformative use that creates a new, valuable (in the sense of worthwhile) product in its own right, without which society would be the poorer.