Previous video capable iPods allowed you to use a 1/8th” adapter for video out but this option has been removed. Now you must use the dock connector instead. The reason is that the iPods now require a video ‘authorization’ chip to be embedded in the accessory (cable or dock). It doesn’t seem clear whether this is a new DRM requirement or a simple accessory tax on Apple’s part.
While the 3rd party product, Monster iTV Link for iPod, uses the dock adapter it doesn’t embed the authorization chip so can’t display video on recent iPods.
One benefit to the Apple video cables is that they include an AC/USB power adapter so you don’t need to buy a separate charger. Ironically, this makes it one of the first accessories you should buy with a new iPod rather than one of the last.