I don't have time to watch the video, but going back over the (real) history of the FBI there are a lot of issues. J Edgar was efficient, but power hungry and probably corrupt although at the time there were no laws against much of what he did. We know that he engaged in blackmail against MLK and likely against the Kennedys and others. There are a lot of questionable deaths around the early FBI and looking back at both JEHs positions and those deaths, it's not too much of a leap to think he had a hand in some, if not all, of them.
Since people tend to mentor those of like minds, it's pretty easy to see how the FBI corruption has snowballed over the years. Not only have they messed up some huge cases and caused needless deaths, but they missed some easy gets and caused needless deaths.
As someone who was once a fan of what I thought the FBI was, it is distressing to find out what they actually are. It's not a party thing, but a power thing, and post 9/11 both they and the other agencies have done some highly questionable and illegal things. There have been no consequences even when they have been caught lying to us, congress, and the courts. No consequences = blank check for all of them to continue running a shadow government and acting against our interests.