I suspect it would not be as clean-cut as that. In an average 30 minute news bulletin for instance, I think there are often a few shots pulled in from the AP or similar agencies, or from partner broadcasters. Then in the sports segments the footage is often marked as "courtesy of" and then BSkyB, ESPN, ITV Sports or similar (depending on who paid for the rights). Therefore there is a strong possibility that it would still require a lot of sifting through the rights, which would increase the cost of doing it.