I generally sub in some sort of povray image with text. Name of the group, website, facebook page, whatever, or a still image with audio only text over it, maybe even throw a counter to count down to video. Various creative opportunities depending on how much time and energy you want to sink into the project. If it's at the end, you can do some sort of scrolling text credits like. I dentify the members of the group, CD ordering information, or just the gear list and venue specs, whatever makes whoever happy. I prefer NOT to have to create filler and it easily doubles even triples the work in post. But at times you can't really avoid it. Batteries only last so long, tapes / media cards only hold so much... For now anyway.