to the site penkapchew.
It is illegal because the show isn't licensed to be distributed in that manner. It doesn't matter that the output is the same as legally recording it. As the distribution licensing hasn't been paid for, its theft. Unless of course, the content is licensed for distribution. I believe Channel 4 are distributing content via P2P for a small fee, which is legal, if you've paid the small fee.
Standard copyright includes saying things like "unauthorised duplication or distribution... etc... is prohibited".
Albert_the_dog: It is legal to record shows (I believe that was only after a court case), but not to distribute them.