download videos from sites like nbc or comedy central: rtmpdump on a mac?

download videos from sites like nbc or comedy central: rtmpdump on a mac?

 

i am so new to this that calling myself a newbie would be an over-statement... haha... anywayz... i wanna be able to download videos from sites like nbc or comedy central... and i found online that they are through some rtmp thing... how do i download it? i heard of rtmpdump but how do i get the link that i need to use with it...?

any help would be greatly appreciated!!