Yes you do get true passthrough (the A/V receiver does not process the video) but not necessarily correct (the 75 ohm impedance issue) nor complete (the bandwidth issue).
Most HDTV's autoselect the incoming component video source scan rate (480p, 1080i, etc.) in which case you have no problem connecting both the DVD player and the HDTV source to the receiver and connect the receiver to one of the jack sets of the TV. But double check the TV instructions to be sure.
Generally there is no problem with the needed 75 ohm impedance for the video signal paths through the receiver. Inaccuracy may result in ghosts. You almost always pay a price in dollars or picture quality in exchange for the switching convenience of using an A/V receiver. Even the RCA connections used by the cables are said to be not exactly 75 ohms, the so called BNC (twist on) connections, rare on consumer equipment, are a bit better, and when using a receiver, you use more cables and connections.
Why you want 90 MHz bandwidth or thereabouts?
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