So I watched the video and this seems like a lot of work and money to arrest 8-12 people that got 3-10 years in prison (each) across three undercover campaigns. So when they get out, does the FBI think they won’t disappear into the back country and hate the US even more? To me, it seems the FBI just created a more savvy terrorist with tax payer’s money.

This is probably true, but they also captured them at the point where they were going to execute a murder. So they managed to prevent that. Not sure what's your idea of handling organized terrorism like in the video is though.

ALSO, the title is misleading. Yes this agent infiltrated the KKK but it was the quickest and most boring assignment. Most of the arrests came from a biker gang and The Base.

Agreed, I suppose it's because people know KKK, but not The Base.