Let me approach this theme from my own experience with the history of broadcasting, where for some years I've been dealing with the radio and television of the past, and with how to relate it to the present. As we all know the broadcast media are contemporary in a very special sense. Programmes last as long as they last - and then they fade out with the electromagnetic waves passing into the universe. Aerial transmissions being what they are, these media provide strictly momentary events. Broadcasts are not recordings a distinction which is of course the salient point in dealing with artists and performers rights in the field of radio and television.
Broadcasting is different from the reproduction of item copies.
As we all very well know also, the result of this definition of broadcasting as a momentary event, is that a very small proportion of what went out on the air over the years has been stored as sound or vision tapes or recorded in the broadcasting institutions. No public library has found it suitable to demand a record of what went on the air, at par with the copyright libraries of the world which for centuries have been instructed to store copies of any printed item whatsoever. This deplorable state of affairs have been cleared up since the 1970s, though. Today, electronic signals carrying audiovisual information are defined as part of the cultural heritage as much as print culture is, and most countries have some system of official archives for sound and vision, including broadcasting programmes even if the question of legal rights are not yet definitely solved for such recordings. Because of this, society has lost an important part of its memory.