No, your TV didn't just switch to Star Wars.
That's Harrison Ford (a.k.a. Han Solo) on the screen. He's playing Col. Lucas, the officer under General Corman who helps assign Willard his mission to kill Kurtz. He's not really an important player in the story (this is just a bit part), but you should note that his name is "G. Lucas"—like George Lucas, who directed Harrison Ford in Star Wars, and initially intended to to direct Apocalypse Now (source).
Coincidence? Shmoop thinks not.