Firstly, it's supposed to be taken as a whole. If someone came up to me showing signs of insincerity, not having any ID to show and wanting to pay for something very expensive with a large sum of cash, yes, that's suspicious to me. Same thing with someone buying huge amounts of fertilizer and other bomb making materials.
Second of all, if someone shows these signs, they're not defined as a terrorist. No where in the video you showed does it say "This person is a terrorist if they pay cash".
The goal is to produce leads so that they can investigate them before they do anything harmful to the country. If terrorists have a certain MO that they follow (not having any valid ID, carrying around large sums of cash) then it makes sense for people falling into that MO to be considered "suspicious" by the organization tasks with tracking down terrorists.
Now, you may disagree with this, you may say that they're going too far and they shouldnt investigate people simply because of these reasons---but that doesn't mean that they're trying to define every single American as a terrorist so that they can enslave them.
Edited to add:
Basically, I'm arguing that your conclusion (the reason you claim they're doing this) is a massive exaggeration
Edited by Stellar, 22 February 2013 - 04:30 PM.