You're talking ridiculous technicalities though. The beginning and end result are the same thing, there's very little difference in what's happening, the simple fact that one situation has physical media present, where the other doesn't is completely beside the point.
The difference is while I might lend my book to one or two friends your 'internet friend' is lending his copy to thousands of people. The other significant difference being that while my friend has my book I can't read it unlike your 'internet friend' who can still watch the origional DVD while thousands of other people can watch the copies simultaneously.
While yes in isolation you can say the two activities are the same the cumulative effect is entirely different and warrants a different response.