No, not protesting, on this occasion. This is demonstrating a process or procedure to the class, as a part of teaching it. It is standard practice in many areas, and "demonstrators" used to be the most lowly forms of academic life in universities (despite the fact that many of them did more effective teaching than their high-and-mighty professors, because they ended up talking to the students rather than at them).
But demonstration for learning is not as simple as it looks. I'm not going to specify rules for performing it, because I know from experience how much it varies between, say, basic IT skills, cooking, gymnastics, or teaching...
Those of us who presume to teach teachers are of course always demonstrating our craft as we talk about it, and the "do as I say, not as I do!" principle (the hypocritic oath) is endemic. And yet—as we try to explain time and again—you would not expect me to teach a class of motivated adults in the same way as disaffected 17-year-olds. It is the demonstration of appropriate principles rather than tricks which is needed most of the time.