welfare groups. many are legitimate but some seem to have no purpose other than to allow dark money to flood into the political system. >> they sometimes are spending tens of millions of dollars, but they have no bricks and mortar. they operate out of p.o. box. their money spikes in election years and drops off during nonelection years. these are the trademark qualities of a political committee. >> what is the difference between what you're describing and money laundering? >> not a whole heck of a lot. we have tracked these money flows going through these very complex networks to in part erase the footprint. >> as if this isn't bad enough, these groups can can donate their money to anyone they want, including a super pac and still keep the original donors secret. >> because it is anonymous, how can we be assured that it's even domestic? we have evidence that foreign countries would love to meddle in our elections. >> what you are describing are all things that are threatening our democracy. >> a donation is not a bad thing. it is a perfectly legitimate way to get engaged with your political system. the problem is that there are