"As a brief aside" means that the author was discussing one subject, but for a short time, they wish to give the reader a different point of view or to offer a different way of thinking about the subject. They want to offer more information to the reader. The noun, 'aside' in English is a term sometimes used in plays in the theater. It's when an actor says something to the audience, but the other actors cannot hear him/her. It's like he/she is telling the audience a secret. However, often in writing it is used to say that the writer wants the audience to consider another aspect or point of view.
To buzz through something means to be able to do something fast and easily. For example, I might say, "I buzzed through that test." That means that I did the test very quickly and that it was easy for me. Perhaps, in the sentence you posted, the author might be saying that people reads or browses through the interactive media quickly so they will not focus on advertisements.
I hope that helps.