SETI or Terrestrial Surveillance

I was wondering if anyone has any thoughts on the SETI research as we know the system works by data being collected from an alleged dish receiving signals from space, then segmented into chunks and the data is processed using pc's. Though who is to say that the data is actually from Outer Space and not from the millions of surveillance cameras around the world. Are people who have the SETI screen saver unwittingly helping the governments process all the surveillance tapes. Similar to the network in the UK were computers through surveillance cameras analyze peoples behavior for crime and then report it to the police?
Any thoughts?

Mod edit: to correct spelling in thread title
Mod edit: to correct spelling errors in post

[edit on 1/8/2009 by benevolent tyrant]

can a mod please change my thread to General Conspiracy
Thanks