We consider the Wyner-Ziv problem, i.e., the
problem of lossy compression with side
information at the decoder. Motivated by
applications in video coding, we study
how to minimize the probability that the
distortion exceeds a given threshold,
as opposed to the conventional approach of minimizing the 
average distortion. We obtain achievable exponents
for this problem and expose a tension
in the choice of the test channel; the
optimal test channel balances two competing
error events. The binary erasure case
is examined in detail.