Hi Al.
It's a little complicated.
Some receivers switch component signals, but usually only 2. And among these, not all receivers were designed for HD video. The different video signals have the following max frequencies:
480i Component - 4 Mhz max
480p Progressive - 12 Mhz
720p/1080i - 35 Mhz
So if you are running 3 standard grade video sources, and your receiver has that many inputs - great.
But if you are trying to run Progressive/HD video, check your receiver manual. You want to look for terms like "HD Video Switching" or "100 Mhz bandwidth". If you dont see words like this - your receiver was NOT designed to handle the higher-frequency signals.
Note: It wont hurt anything to hook it up. Nothing will be 'damaged' by pushing HD video through a 'component' capable switcher. But there could be some ghosting of the signal and loss of focus.
You are not alone in needing more than 2 inputs into a video switcher. Here is a thread that discusses this issue and mentions several external switch box's for between $100-$160 that do the trick.
Inexpensive HD Video Switching
Hope this helps.