I think alot of it comes down to how much the BBC cares...if they really wanted to in force the conditions of use...in fact even if they asked me to remove all TG related material than I would without argument...as it is their material and that is that.
I am sure however they would make a start on sites such as this blatantly charging people £2 to download episodes of top gear.
http://www.voodoofiles.co.uk