How do I hook-up the following devices to my TV. DVD, VCR and Satellite receiver (direct TV). I also have a RF modulator box. I only want to use the DVD and VCR as players only. When watching Direct TV and I want to see a DVD movie, when putting the movie in the device it switchs automatically to the DVD player.

You should use a SCART cable between your TV and DVD player.

Remains the VCR , satellite receiver, and standard TV antenna reception.

First connect your VCR to your TV. Via that cable you can display VCR tapes, and loop through other RF based signals.

Combine with a splitter-in-reverse both antenna signals and satellite output, and connect to the VCR rf input. Use a low-loss splitter.

Note : it may be required to slightly change the RF output frequency of the satellite receiver output when they are on the same channel and cause interference. See below.

Remains the tuning of the different units to each other.
Start (1) with adjusting one channel of the TV to the VCR (run a tape to be sure you adjust to the VCR output).
Than adjust the satellite receiver output frequency if it interferes with the VCR output. If you can't, change the VCR output frequency slightly, and go back to step (1).

Now adjust the TV with a second channel to the satellite output and all remaining channels to the various standard antenna reception frequencies.

Success !

:)

You must provide a description of the output ports available on your Sat. DVD, VCR and inputs of your TV.

Most vendors assume that you will be using a A/V Receiver to bring all of the inputs into one unit and then that unit communicates to the TV for Video and Audio goes out through the A/V's Digital sound processor to your speaker set.

BTW - A SCART cable a A/V cable design and port that is a standard in France. It has not really taken hold here in the U.S. HDMI seems to me to be the connection method favorite for this minute in time!