[rtmpdump] I got the error message when trying rip video from mtv.com

[Yuen Bun Ng]

here is the command:

>rtmpdump.exe --debug --swfhash f58ead8855e7e2d
5efaceac43e4d1e920263950fbf2109bba3f291f6cb8c3280 --swfsize 283231 --swfUrl "htt
p://media.mtvnservices.com/player/release/?v=4.2.0" -r "rtmp://cp10740.edgefcs.n
et/ondemand/mtvnshrdstor/_!/mtvi/bands/b/beyonce/video_phone_remix_full_256x144_
300.mp4"

source:http://www.mtv.com/videos/beyonce/455581/video-phone-extended-remix.jhtml#id=1518072

I received the message "ERROR: RTMP_ReadPacket, failed to read RTMP
packet header".

Anything I did wrong? I use the URL snooper to found the link.

thanks.