Kindly recommend me one 1:4 Video Buffer. Signal will be either YHV, Y/C, RGsB.
You might look at a MAX4022, https://www.analog.com/media/en/technical-documentation/data-sheets/MAX4014-MAX4022.pdf.
One chip can implement with good design a single channel 1-4 buffer, 3 chips would be able to handle your sources.
Also might check out AN57 www.analog.com/.../an57fa.pdf
If you come up with a schematic, we can review it.