"B-Roll" is archived footage that TV news will use to relate to have something visual to show for a story that they don't actually have footage for. Like for a story about tourist in San Franciso they'll show the same cable-car-golden-gate-bridge-crookedest-street you've seen a thousand times.
"A Fox affiliate in Connecticut was forced to apologize several times yesterday after it aired b-roll of female breasts to illustrate a morning news report on a "Women's Day" event being held in the state Capitol." (gawker)
Ha! What's funny to me is how the TV station must have this footage filed so that when they needed b-roll for "women" this is what they used. Or there's an intern being yeld at by the producer to find some b-roll, and they're probably saying, "but, the only thing I can find doesn't really fit thi" "JUST PUT IT UP DAMN IT!" Or it was someone's last day and thought this would be funny; they did play it twice...