Riddles.

Here is a riddle whose answer has been encoded. Letter substitution is consistent, i.e. if B represents D, then it does so every time that letter appears in the answer. A vowel does not necessarily stand for a vowel. Use what you know about the frequency and placement of letters in English, repeated letters in the encoded sentence and the series 1 DVD commentary to decode the answer.

Why did Chris Barrie’s hair seem to grow between scenes?

Bau duft hipuh apt duf.