A vocoder just makes the voice sounds robotic. Auto-tune changes the pitch
Actually, the vocoder does both, as it imposes a pitch or chord upon a voice. Or strictly speaking, it's the other way around: it takes a sound source then alters the dynamics of the each frequency band in that source to match the dynamics of the voice: in crude terms, it makes an instrument talk rather than giving a voice a pitch. Wikipedia has a useful summary. The only reason it sounds "robotic" is that the multi-band filtering and dynamics-following are only approximations to the dynamics of a voice. The more accurate the processing, the more natural it sounds.
Which takes us to Auto-tune, which is in one sense a more sophisticated vocoder. As the article says, the intention was always to sound natural, and most Autotuning will be transparent to us. It's only when they tweak it to sound like a deliberate effect that we notice it like this. This video is clever since, unlike most of the pop/R&B uses of it, the effect is made even more obvious by using external sources.
A lot of innovations in electronic music come from mistakes or deliberate misues of equipment that was supposed to make things cleaner and more pseudo-natural, or from outside the world of music. Vocoders were for voice compression & encryption before Walter/Wendy Carlos did A Clockwork Orange and Kraftwerk did Autobahn; the TB-303 was supposed to sound like a real bass guitar, not like a squealing bout of acidic mayhem; the famous machine-gun kick drum in Blue Monday was meant to sound like a soft echo; and of course guitars were never supposed to be fuzzy.
No one wants me to embed Frampton Comes Alive up in here, do they? DO THEY?
go on....... embed the Frampton!... Frampton haters (including myself) can step off... nobody's going to force them to click that link... hell, i'd embed it myself, but things like that have got to come from the HEART, y'know?...
A vocoder just makes the voice sounds robotic. Auto-tune changes the pitch, which is why the newscasters speech has become tuneful (as well as robitic) in the video.
[muso geek stuff] IMHO better than both of these is a Harmonizer which can sound truly awesome. I have very happy memories of an evening session I spent with a group of mates, a microphone and a harmonizer plugged into a stereo (and lots of beer). They don't get used that much in home studios as they remain quite expensive and software emulators don't come close to the real thing. However I have to take my hat off to people like Michael Tretow who created Abba’s famous wall-of-sound vocal harmonies without any of this digital studio jiggery-pokery (and didn’t shoot anyone either…)