It is HDMI over fiber and the correct way to do it.
Balun was the term when we were sending analog signals over copper (cat5e/cat6) and transorming the signal from unbalanced to balance and hence the term.
You can still send the HDMI over copper using baluns but you can not get over 10Gbps and hence no HDR and 4:4:4.
Another option is to get an active HDMI cable, 50 feet is not very long.
The best option is fiber by far and you have two options:
1) Use a “propriertary” fiber cable with detachable ends. I have used a Celerity cable and it can send full 18Gbps HDMI over 150 foot. There should be
http://www.celeritytek.com/product.html similar products by others.
2) Use a standard fiber cable by Cleerline or all the big players and then use active electronics (balun) to send the signal. Similar to 1) but more future proof.