Another thing that would be interesting is to look at the effect of non-uniformly distributed birthdays. For example, the day that's nine months after valentine's day or christmas might (?) have a slightly higher number of births than an average day. Then you could look at what kind of an effect this would have on the probability of a common birthday as a function of group size.
He gave example from some text taken out of bible with spaces removed. That's lots of letters on one screen, and from those letters he was able find his name, date and topic of the talk, when joining letters at equal distance.
Finding unbelievable patterns is not as amazing as we think.