We only have one Scart socket on our TV so we wanted to avoid swapping Scart leads for our DVDs, VCR tapes and PVR.
This does the job well just by selecting the button for the device that you want to watch.
We have seen no signal interference between the devices. Devices other than the one you are watching need to be on standby though otherwise one device stops the signal from the second getting through.
Note in the first place we mistakenly ordered a Scart Splitter to do this job see my review on: Ex-Pro Premium Silver 3 Way Scart Splitter, Shielded cable, stress reliefs. 21 Pin Fully screened connections. 2 Year Ex-Pro warranty.
[Can't give a link as product is currently unavailable.]
Also note you will need an extra Scart lead to connect to the TV.