Are "Component Video" inputs useful on a receiver? In what way do they benefit your Home Theater system? Is running your TV and DVD through them better than connecting them to one another?
Its a matter of convienence. When switching audio sources on the AV receiver you would like the video to follow.
On a fully connected system (ideally) one remote would control the program material through your monitor and speakers. There would not be the hassle of matching the video with audio portion of the program.
With TV tuners, cable boxes, DVD's, and mix-match collection of audio equipment, you end up with some combination of the above and a multitude of remotes to control everything.
My vote is for switching convienence. (and No the quality does Not improve with more connections!)
Yes, The same pertains to all video on an AV receiver. Most consumer receivers will not up/down convert the signal so the level of video input is what is output when that source is selected.
So, input VCR on Composite (yellow RCA) and that is going to be the monitor output when that source is selected. Input the Satellite box on S-Video and that will be what the monitor output when that source is selected. You get the idea.
Matter of convienence.
I usually set up the monitor (TV) in a method that takes the lowest input as INPUT 1 and progressively gets better as you move up the input chain. So I might have Input 1 as the RF input (antenna/Cable) and Input 4 as the Component Video (DVD). Etc.
In my experience, at least for video, the most direct path produces the best picture. This is not always practical advice however, when someone has multiple devices and minimum tv connectivity. Some receivers do well at transferring an image with minimum degradation, others do not. I have found that quality av switchers generally do a better job for video purposes.
What Dale is trying to say... well I don't know what he's trying to say, but if you don't need the ability to switch Video because you have the latest monitor with umpteen video inputs, you should go direct.
However, like some of us, you will have multiple sources and limited monitor inputs, so the AV receiver makes switching much easier when going from source to source. Usually, the quality is dependent on the signal type. I believe most manufacturers would carry at least unity gain ( 1 to 1) on signal quality through from input to the monitor output, so degradation would be a product of poor cabling. (Caveat: There are some cheap receivers out there!)