United has gotten worse and worse with this. The ads after (not before) the safety video, and also before each movie you watch (and it's usually the same ads before every movie). A few years ago the ads were skippable, but not anymore.

The flight attendant also makes an announcement about the United-branded credit cards near the beginning of the flight.

But this is really just an illustration of what the top-poster of this thread said: flying people places doesn't make enough money, so they have to pursue other revenue streams.