Re: DRM can´t work,
Lets look at this example... "I know of two sisters aged 12 and 14 who regularly buy the same music from iTunes."
There is NO DRM on iTunes music. Yet they still bought it anyway. Just copying the file was too much trouble.
The real question is if they removed DRM how many people who buy now would start making copies. How many who copy now to avoid DRM would buy a DRM free file.
I have not seen anything to indicate that removing DRM and offering people an easy way to buy would result in a loss. Looking at the removal or DRM on music downloads I don't see where it crashed the system.
The only place DRM is reasonable is for rental files (it still will not stop people making copies).