Thanks for your query. In the living room I have a 47" Panasonic Viera slim TV (connected to the Panasonic Viera Blu-ray); in the bedroom a 32" Panasonic Viera slim TV. I use MEDIALINK and in the living room have the ROKU 3 and in the bedroom the ROKU 2 XS. To get the bedroom up and running I had to run a 50' Ethernet cable from the living room setup down the wall and up the wall to the bedroom ROKU. Both setups are actually only about 3' from each other through the wall. Over the weekend I had no problems getting HD programs to play through the bedroom ROKU to the PLEX programs which are on the living room computer. I can also use the bedroom ROKU, if I don't use PLEX, with streamers such as Amazon PRIME and the excellent British TV programs on Acorn Media. So, if I want, I can shut down the living room computer to get Amazon and lots of other ROKU streamers. In the bedroom I was able to watch all the HD programs with no problems except for the two Herman Wouk series. When I download from YOUTUBE, I HAD been downloading the highest quality MP4 format available. I have a Dell Inspiron 660s running at 3.30 mghz with a 1 TB internal hard drive and all the downloaded programs on an external 3 TB hard drive with USB 3.0. I only have 6 MB memory. The computer only has 2 slots for memory chips - sneaky to fill with a 4MB & a 2MB! Sorry, don't know what transcoding is. When I play a program on the computer I just go to the folder where the download is and click on which brings up Windows Media Player. I could never get the "bookmarklet" to work; I found that INTERNET DOWNLOAD MANAGER is very good as I can load up a boatload of stuff to download during the night and if there is a problem, then that is easily fixed.
It is obvious that there is a glitch in the setup on the living room Panasonic TV. I shall have to study the manual again; this TV has an Ethernet cable outlet connected to my setup; maybe that is where the problem is. It does not have much in the way of streaming outlets such as ROKU has. It was bought "Wi-Fi" ready.