How do I fix this Smart Folder problem? It keeps switching off of "This Mac"
Here's the steps I used to do what you're looking for which seem to be working the way you want.  

Open Finder and click File > New Smart Folder - or press ⌥⌘N

Then setup as I have in the screenshot below and click 'Save' near the top right.  



Then, when the little drop-down menu appears for you to save, select the options like I have below.  



Now, you'll get a window left behind like this.  



Now, close your new Smart Folder.  Then in Finder, open a normal finder window with either File > New Finder Window or ⌘N  

Your 'TV' Smart Folder will be listed under the 'Search For' section on the bottom-left if you expand it out, like so