You should sell your idea to JRiver and then they could build this feature in.
They can use it for free.
I know that since I wrote that, they've actually improved the behavior of the built-in Watched() expression a bit, but I still like this solution better. It works perfectly with the Mark as Played/New functions they have built in now (I
still want a way to toggle that from Theater View though). I do wish more of this kind of thing was "pre-done" in this regard on a fresh install, though.
If done though, I prefer that it is done "within" the system (as I did), as opposed to using "magic" expressions like Watched() and TVInfo(). That way users can go in and tweak the pre-done views and learn from them. The expression magic functions are just black magic.
But a default Library could
use a lot more of the functionality right (fonts, useful calculated fields for display, and whatnot) right out of the box.