Great question — answering as the UphillTech team:
Is there some rule/regulation from the content providers that say when broadcasting on TV they have to add a station logo? Only because they've bought / recorded / invested their own money for the broadcasting program. It's a copyright. What will they do, if you record their program and broadcast on your own, or just sell it somewhere? ( similar to plagiarizing ). Other than their logo, the stations also use some kind of watermark in their channels that can be easily noted if you closely look into it. It is much visible if you record the event. This wiki article is good.
Full answer by anon: https://movies.stackexchange.com/a/10622 (CC BY-SA 3.0).
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