For video, yes. Most a/v receivers out there only do audio playback from USB. Occasionally they may do video from an iPod, but that requires the video be generated by the iPod and it usually is a bit fancier than a USB cable (mine uses a specially made docking station).
It's easiest to think of a receiver as being an audio only device - they acquired minor video switching and processing capabilities out of necessity. None are as capable as a media box (especially since they really only got popular the past few years when Apple made a big fuss with the AppleTV).
So far, given the variety of media formats and such, it's probably better that way - your receiver you're likely to keep several years, your media box, well, they're so cheap and things evolve so quickly it'll be outdated in a year.
It's also one of the hardest things to decide about a receiver - do you go for network capabilities or just get one that doesn't and use one of those boxes to give you the same capabilities.