Some rooms fill up really fast, when the room is full they start denying access to the room, for obvious security reasons. If there is a talk that you don't wa

Some rooms fill up really fast, when the room is full they start denying access to the room, for obvious security reasons. If there is a talk that you don't want to miss, arrive before the previous talk ends, this way you'll be able to enter as soon as the previous talk ends. On really popular rooms it has happened to me in the past that no one got out and I was not able to attend the talk. Since (almost) all sessions are recorded and made available soon after FOSDEM ends, I watched it at home later.