Rules for Copying Presentation Style?

In a previous post - Video and Screencast Styles for Corporate Training? - I had mentioned Common Craft as an example of a particular well-known style that seems to have struck a chord. I'm still looking for examples of other good styles that people have seen.

In the meantime, I ran across a post by Ewan McIntosh who points to a video by McKann Erickson (the big ad agency) that uses the same style as common craft. Ewan tells us -

It's a shame that one of the largest ad agencies out there, McCann Erickson, feels the need to rip-off others' work, without even a casual link out to the people they're attempting to copy. ...

Why, then, have McCann repackaged/stolen the idea and produced something that's mediocre at best, plain boring rather than plain English?

I'm wondering about this. This is obviously a rip-off of the style used by common craft. And as Ewan tells us, it's not well done. They slip into power point looking stuff along the way. The humor isn't really there. But the question this leaves me with ... if I found something that I thought was a good style to copy for the videos and screencasts that I'm thinking about, I was planning on borrowing from it. Would this be wrong?

What are the rules for copying presentation style?