Juniper Netscreen: How do I capture debugging (debug flow) information

From the command line interface (CLI):

!Turn on the dbuf buffer
set console dbuf

!Set the parameters for debugging
set ffilter src-ip 192.168.10.50

!Turn on the debug flow
debug flow basic

!Use debug flow drop command to see dropped or denied packets (including those that did not make it to the policy engine).
debug flow drop

!turn debug off
undebug all

!check captured the stream
get dbuf stream

How do I capture debugging (debug flow) information?