CloudShark can decode Kerberos packets using a Kerberos keytab file. When a Kerbose keytab is available, CloudShark will consult this file to see if any encrypted kerberos traffic can be decrypted.
Creation of the Kerberos keytab file is documented on the Wireshark Kerberos Wiki
Kerberos encryption is enabled by adding the following entries to your decode options:
kerberos.file: <path to key tab file> kerberos.decrypt: TRUE
kerberos.file: /home/cloudshark/krb5/816.keytab kerberos.decrypt: TRUE
Make sure you follow the instructions on updating the decode options when adding the new kerberos entries! CloudShark may need to be restarted to see the new decryption results.