You could also try reading THE SYNTAX of the command on the wiki because I have no clue HOW or where you got the syntax you're using.
freeswitch@taz> uuid_broadcast 45003110-d8e8-4e52-a871-3499617562a7 /usr/local/freeswitch/sounds/en/us/callie/digits/32000/star.wav
+OK Message Sent
2010-05-21 09:26:43.324866 [DEBUG] switch_core_session.c:861 Send signal sofia/gateways/9999999999999@192.168.1.113:5062 [BREAK]
freeswitch@taz> 2010-05-21 09:26:43.464862 [DEBUG] switch_ivr.c:551 sofia/gateways/9999999999999@192.168.1.113:5062 Command Execute playback(/usr/local/freeswitch/sounds/en/us/callie/digits/32000/star.wav)
EXECUTE sofia/gateways/9999999999999@192.168.1.113:5062 playback(/usr/local/freeswitch/sounds/en/us/callie/digits/32000/star.wav)
2010-05-21 09:26:43.504860 [WARNING] switch_core_file.c:176 Sample rate doesn't match
2010-05-21 09:26:43.504860 [DEBUG] switch_ivr_play_say.c:1152 Codec Activated L16@8000hz 1 channels 20ms
2010-05-21 09:26:44.004844 [DEBUG] switch_ivr_play_say.c:1444 done playing file
uuid_displace <uuid> [start|stop] <path> [<limit>] [mux]
freeswitch@taz> uuid_displace 4cdb1202-e8f1-4fa1-a189-424602720df0 start /usr/local/freeswitch/sounds/en/us/callie/digits/48000/star.wav
2010-05-21 09:28:03.860705 [WARNING] switch_core_file.c:176 Sample rate doesn't match
2010-05-21 09:28:03.860705 [DEBUG] switch_core_media_bug.c:365 Attaching BUG to sofia/gateways/9999999999999@192.168.1.113:5062
+OK Success
Its an API call not an application to execute.
/b