Coaxial CATV to power line adapter
There is not really such a product since power cables are unable to carry the bandwidth needed for broadband signals such as CATV.  The best you might be able to do is a remote video sharing device that is hooked to the CATV tuner.  These devices take HDMI from your video source, transmit it over WiFi, and then turn it back into HDMI at the receiver.
This article offers some options:
HDMI over WiFi
To quote a section:

The Iogear GW3DHDKIT Wireless HDMI Digital Kit is the best HDMI
transmitter for most people. Using WHDI, it delivers the best image
from the lengthiest distances, has two HDMI inputs, and can be powered
via an included AC adapter or your TV’s USB 3.0 connection (cables not
included). It’s also the least expensive dual HDMI unit we tested.

I know nothing about this particular unit but it or something like it may do the job.