So since we have to describe Digital Ethnography, first things first: go to Wikipedia for a definition of the big word
Ethnography (ἔθνος ethnos = people and γράφειν graphein = writing) is the genre of writing that presents varying degrees of qualitative and quantitative descriptions of human social phenomena, based on fieldwork. Ethnography presents the results of a holistic research method founded on the idea that a system's properties cannot necessarily be accurately understood independently of each other. The genre has both formal and historical connections to travel writing and colonial office reports. Several academic traditions, in particular the constructivist and relativist paradigms, employ ethnographic research as a crucial research method. Many cultural anthropologists consider ethnography the essence of the discipline.
So obviously, on this site, the human social phenomena that is being studied is YouTube. By having the students make a presence on YouTube, they immerse themselves in the culture of the site in order to get a better idea of its community and implications.