A different work around I found for Windows 8, because there is no actual Netflix program to make a caster channel from, just the ModernUI app. So here's a work around for those who want:
All you need to do is make a shortcut in your caster assets folder, I also made a subfolder called Netflix, so that is what i will use i in any example paths. Right click, new shortcut, and put "netflix://" without quotes in the destination. Now you got a shortcut to the modern app. Unfortunately caster won't accept a shortcut, so the next step is to make a batch file to run said shortcut. Make a new text document and type
start C:\Windows\explorer.exe "C:\Caster Assets\Netflix\Netflix Shortcut For Plex Home Theater.url"
put your shortcut path and file name in place of example path/file name.
Now follow casters instructions on creating a channel and bam, netflix back on plex!
I've included Netflix caster assets (including an editable batch file, logo, icon, description and shortcut) in the Netflix.rar so you don't have to make your own if ya want. Should be able to just extract that to your caster assets, make caster channel n go really.
Now for a new problem! You watch on your big screen? No way to control Netflix because your mouse is by the computer? The Netflix modernui app usually opens on the primary monitor..so unless you have a setup where your tv is primary and have a keyboard and mouse next to you on your couch or something else going on (in which case i'd like to hear). You will need a way to move the app from one screen to the other and control Netflix. For this I use xPadder Netflix profile and another little trick which continues off the files from the previous caster setup.
If you want complete control the easiest way i found is to make another shortcut FROM the last shortcut you made (the netflix:// one) but not just any shortcut. Hold shift and right click the first shortcut, click "copy as path". Now create a new shortcut and put explorer.exe and paste what you just copied.
i.e. explorer.exe "C:\Caster Assets\Netflix\Netflix Shortcut For Plex Home Theater.url"
This is so you have something that will let you pin a Netflix shortcut to the taskbar, because the first shortcut won't let you. You can now change the icon of this new shortcut with the Netflix.ico provided if you'd like. Then pin it to your taskbar, slot 4.
Next, pin PHT to your taskbar, slot 3.
In order for the xpadder profiles provided to work, they will have to be pinned in those slots.
Also, these profiles were made for a Logitech Rumblepad 2 controller, so you may have to tweak this for whatever controller you use.
Get xpadder first obviously, (http://xpadder.com.). Have it start automatically with windows.
If you have a rumblepad you can open the controller profile provided for your it. Or make your own with your controller.
Download the xpadder and netflix.rar included, extract where you want, probably in "C:\Program Files (x86)\Xpadder"
Now in xpadder. Use the auto profile option in xpadder (click the wrench settings icon), check the "activated" box and make new auto profiles that watch the right programs and switch to the right profile when that program is in focus.
For PHT:
Click "new", open profile (open Plex Home Theater profile provided), click "select program" and tell it to watch plex home theater.exe (C:\Program Files(x86)\Plex Home Theater)
For Netflix:
First open netflix, so it appears in recent windows. Back in xpadder, click "new", open profile (Open Netflix profile provided), click "recent windows", click "ok" and select Netflix from the list by click "select program"
Now you should have full control of both PHT and Netflix.
Right analog stick in Netflix will be your mouse, left will be to scroll.
"2" is left mouse click in Netflix and Enter in PHT.
"Start" will launch PHT from scratch or refocus it when needed.
D-pad right will launch netflix from Plex also and switch the Netflix app from one monitor when focused on Netflix.
"Start" will exit Netflix and should refocus on PHT, switching xpadder automatically back to PHT control.
Look at the other buttons configured in the xpadder provided profiles to know what they do.
Hope this helps some people! Try caster with GameEx properly configured too! Good fun.