Is recording someone really a felony?.
Are you really asking this when about 20 seconds of googling would tell you? Wow. Not a fan of facts, I see.
In many states, recording audio when all parties have not agreed is very very illegal, yes. California is one of these states. The laws are complex, full of caveats and details, and vary between states and between audio and video recordings. Shows like "Marketplace" are very careful to stay on one side of the law. These yahoos were not, which means they probably committed a felony.
Also, shows like Marketplace tend to release excerpts which, when you hear the full clip, give a mostly accurate picture of what was going on. These guys edited the excepts, including mis-matched questions and answers, to give a false picture of what was going on. Some judges are lenient towards people who expose criminal activity, but few are lenient towards people who try to frame innocents.