Use of iconic toys in videos

Now here's an interesting question, posed this weekend by one of our readers:

"I work for a company that hosts film competitions online. Our community of film-makers competes to create short, branded films for our corporate clients.  

We've had a couple instances in which film-makers have used iconic toys in their videos, such as Barbie dolls, Lego bricks and, most recently, a Brio train set:

I was reading in your blog about Lego's attempt to trade mark the shape of their blocks, which was ultimately unsuccessful - as it was deemed that the shape of the Lego blocks generates functionality. However, I wasn't able to resolve my question: can our film-makers legitimately make use of trade mark-protected iconic toys in their films? The films our community produces are commercial ventures, as licences for all of them are turned over to our clients, and a select few are awarded cash prizes".

Says tytoc collie, there are some interesting issues here -- which he believes that our reader will have to determine on a jurisdiction-by-jurisdiction basis if the films are to be used or accessed in more than country.  For example, is the trade mark-protected iconic shape also protected by copyright and/or design rights? Does the principle of exhaustion of rights apply, or might a use which the trade mark owner regards as derogatory enable it to exert its rights?  Please post your comments below!

Merpel notes that Barbie is a popular target on account of her iconic status.  Unauthorised works which incorporate her include "Barbie's Audition" here, "Superstar: the Karen Carpenter Story" here, "Food Chain Barbie" here and the song, "Barbie Girl" here. Is there any means of quantifying whether this use of the icon, aimed at an audience older than that of the doll itself, has any effect on the power of the brand, she wonders.