In terms of the actual production, I treated this like a travel vlog, in that I did intro -> b-roll -> short update -> b-roll -> summary. This was my first hackathon, so I wasn't sure what kind of format to go with. So I went with one that allowed me the most flexibility. Now that I've been through it & generally know what to expect, I would probably go with the same format, but I can't say that I won't go with something different.
I was also really caught-up in the event, and being a newbie to the community, I didn't want to burn bridges with the other developers before I had a chance to build them. Even while I was there, I thought of better b-roll shots than what I took, but they would require more equipment than I felt other people would be comfortable with. Even though vlogs are more commonplace now, and less people are weirded-out by others documenting their experiences, a lot of people aren't comfortable with someone else posting their faces and/or voice on the Internet. As I get more & more integrated with the developer community, my approach to vlogging at a hackathon may change.
You can watch the vlog on my YouTube channel here.