High Definition Video Distribution - all your hi def video to all your TVs.
Time was when the furthest you could run an HD video signal was about 10m, based on the limitations of an HDMI cable.
Nowadays, as if by magic, simple old CAT5 or CAT6 cable can carry Full HD & UHD signals for hundreds of metres, using HD over CAT6 converters or HD over IP converters.
We have successfully installed many of these multiroom systems, and have distributed a single BluRay player, Sky box, PS3 etc to any TV in the house. Using matrix switchers means any source can be played on any TV, at any time.
Of course, we still can't stop the fighting over which channel to watch ! But then, you can always get more than 1 PVR or BluRay player !!