I can't remember who it was now, but an older musician I was interviewing made the point to me that all those legendary secret or small gigs of yesteryear that you heard about afterwards would seem a lot less mythic if there was poor quality phone footage of the event already up on youtube by the end of the night.
So I really think people should respect Kate's request. It's going to be a special moment; immerse yourself in it, and let someone else worry about the documentation!