1) Stephen Colbert was due to interview Texas Democrat candidate James Tarrico on his chat show.
2) There is a rarely imposed FCC regulation about "political balance" that states if a news or current affairs program has a politician being interviewed then a politician from the other side must also be interviewed. This regulation explicitly EXCLUDES chat shows.
3) PARAMOUNT, which is the corporation that owns CBS, the channel on which Colbert's show airs, needs the approval of the Trump administration to complete a major business merger.
4) The head of the FCC, Brendan Carr, wrote to CBS telling them that he was re-interpreting the regulation and the Tarrico interview could not take place. CBS's lawyers informed Colbert that the interview could not be broadcast and that Colbert could not inform the audience as to why.
5) Colbert, nontheless, DID say on air that the interview had been suppressed, and why. He then recorded the interview off air and posted it on his YOUTUBE channel, having told the studio audience and viewers of the broadcast show, "If you go to our YOUTUBE channel you might, coincidentally, discover that an interview with James Tarrico has somehow appeared there".
So much for the First Amendment protection of free speech.