1. Like a star field, here are so many stars that you have trouble singling out anything interesting
2. Like the ‘bigger dipper’, ‘the archer’, etc it is supposed to show or signify something to one person but to others it is impossible (or very hard) to recognise
3. A group of related features
In the talk the phrase was in the context of applications like Word where there are so many things to choose from that the user is simply bewildered and will find it difficult to focus on the task they wish to complete, i.e. (1). But I rather like the other definitions too, especially (3) which conveys the opposite message.