More to the point, what the hell is a cat-5 HDMI extender? I saw one selling for over $500, and the first thing I thought was, "why not just by another computer or one of those media player boxes." Or why not spring for one of those DLNA TVs? Answer: because people are ignorant.
Here's how you can set up a separate computer for playing video. First buy a used computer, like a P4 or a dual core, and install a nice video card with HDMI out that will also do 60FPS. Buy a Blue Ray drive for this other computer, if you want to watch Blue Ray. Connect the computer to your network. Then, install VNC, the remote control solution. Now, whenever you need to control the unit, use VNC to remote-control the computer.
It's great for people with poor eyesight, because you can watch either screen - the one on the TV or the one on your laptop.
Now your TV can be as far from the computer as you want. You can even use a VPN like Open VPN to establish a link across the internet, and remote control the TV's computer from a computer miles away.
Another thing about these devices is stupid: some use dual Cat5 cords. Look at this:
According to these numbers, transmitting raw, uncompressed HDTV should not exceed 300 Mb/s. That's 1/3 of a gigabit ether link. Why do these extenders advertise that they go up to 2Gb/s when the most wasteful signal you can transmit should be 300Mb/s? Then, factor in that regular HDTV uses only a little more than 100Mb/s uncompressed, and most programming is delivered using an MP4 stream, which has a 20Mb/s bandwidth requirement. If you're just watching MP4 files, you can deliver the data over an old 100Mb/s network link.
Don't even get me started on the nonsense about needing to use quality cable. You just need a functional cable. Cat5 cable is inherently shittier than any HDMI cable. Cat5 is just regular phone wire twisted and arranged a specific way. HDMI is a better connector - but Cat5 has better range because it's a packetized, fault-tolerant, digital signal, with electronics at both ends to deal with the cable's lameness. Smart digital usually beats stupid analog, most of the time, and at lower cost.