OK... since people are not chiming in, here I go.
The wireless gizmo linked by the OP costs $60+ and transmit a video/audio signal up 150 feet (or so it claims). It has both RCA and Coax connectors on the back:
The gizmo might give the impression that one could connect the cable tv on the transmitter and magically receive all channels on the receiver. That *IS NOT* how it works. The Coax "out to tv" connector is to be used when your tv has no RCA (think ATARI channel 3/4). The "antena" connector is just to use it as bypass in case you have an antenna source.
The transmitter is designed to be plugged into a source (cable tv box for example) and transmit whatever comes out of that box into the receiver. You can not see anything else other than the channel being transmitted. Whatever the clients are watching, that's what you gonna watch in the kitchen. If you want to change channels, you have to walk the 100 feet and change the channel over there, hence, an IR extender is included.
Please note that IR extender is "a cable", ergo, using it defeats the purpose.
Because of the aforementioned limitations, Rube recommends:
100 feet of good old coax, for $7.15
Just staple/glue the cable into the walls and paint it the same color as the walls, nobody will notice. Or get yourself on that attic, is not really that scary, I do it all the time.
"Hoy es un dia normal, pero yo voy a hacerlo intenso" ~ Juanes