I hope I understand this correctly:
Here is what I did. I have 3 HDTV (none have networking) I added a small fast computer with a good Video Card to each TV via HDMI. All the computers are on the network (CAT6). I have a server; however you could use one of the machines as a server and store Videos. I download my DVR to my server and then can play any video on any TV in any room. I can have all 3 TVs watching different videos at the same time.
As far as the BluRay Player I only have it connected to one HDTV in the main living area. Typically we just watch BluRay Disc in that room only. You can run HDMI over Ethernet but it requires expensive equipment and 2 CAT6 wires for each device. Not really worth it. If I really need to watch a BluRay movie somewhere else I normally plan ahead and RIP the BluRay to my Server then I can watch it in the other rooms. (Note: This is a BluRay I own, not rented, or borrowed)
Hope that helps -WS