While it was originally designed for study abroad pre-departure courses, Anthony Ogden's YouTube Ethnography Project is easily adaptable to a COIL context. Here is what I would do: 

1. Put COIL students in diverse pairs or small groups. 

2. Have them complete Step 1, creating their own videos. Alternately, they could find existing videos that represent their own culture(s). 

3. Instead of framing their ethnographic research on YouTube as trying to understand their host culture, have them search for and analyze videos related to the culture of their diverse teammates, including the videos those learners have already posted. 

4. Team members can serve as cultural informants for each other, responding to conclusions drawn in the ethnographies when they are presented to the group.

I have found it useful, when teaching study abroad students to use ethnographic methods to do two additional things:  give them a short reading on the sorts of things that anthropologists often study (kinship relations, gender roles, etc.)  such as https://www.nps.gov/orgs/1209/what-is-cultural-anthropology.htm  and tell them they are learning to practice curiosity (asking deeper questions & seeking out the answers) and openness (not assuming that the answer they found is the one right answer).