This paper aims to present how video production is impacting the classroom, mathematics students and teachers in Brazil, as well as mathematics knowledge production developed with this media. Digital video Festivals with mathematical content are being implemented in Brazil, locally and nationally. One of them is Mathematics Education Digital Video Festival, organized by the Research Group in Informatics, Other Media and Mathematics Education, GPIMEM. In this century, video is earning space as a pedagogical approach in either face-to-face or distance education, even before the COVID-19 pandemic. Currently, considering social distance, the use of videos became an imposed reality to students and teachers. Students and teachers with different level of experience or age started to realize possible positive effects regarding the reorganization of the classroom by the presence of mathematical videos. However, other aspects provided negative effects: for example, inequalities in homes and mobile access impacted equal opportunity to all. This paper will summarize the use of mathematical video in the last century and discuss what is happening this century. We will revise some research developed, mainly in Brazil, that shows how the classroom does not fit in a parallelepiped model. Internet, videos and software combined are "things" that have agency and are co-participating in learning and teaching mathematics. The organization of festivals of videos have become important not only in Brazil but elsewhere in many formats either nationally or internationally, in a way to create challenges, exhibitions, cultural mix that aim to show mathematics applications to the general public. In particular, this article reports on parts of a qualitative research that investigated participants of the first edition of the referred national festival. As a result, we look for the comprehension of following the discussions of qualitative transformations regarding the use of videos in classrooms and mathematics knowledge production, as this new setting suggests that digital technologies arrived in XXI century to collaborate with learning. This article will be supported by a theoretical perspective on technology based on the notion of humans-withmedia. In such a perspective knowledge is seen as being constructed by humans and different media and different artifacts. This article shows how such a perspective may help us to cope with the classroom of the XXI century, including the classroom that during the pandemic include students' and teachers' homes.