Can anyone explain to me what a proprietary ad is?¿?

Answer 1

In the business sense, propietary means the ownership by an individual or corporation of a product by virtue of trademark or patent.

When a company pays for an ad it is their property. Therefore, calling an ad proprietary is redundant. However, elements of the ad (such as a slogan) can be propietary. Example: Wendy's "where's the beef?" slogan in the 80s. Any good slogan, or concept that becomes identified with a brand (and is trademarked) is considered to be proprietary. This allows the company to address any trespass or infringement by other bodies.