I do remember that now, but I too was drunk when I read it and forgot to circle back to it. I was thinking about it this morning however, and also the other day when I was looking for Bad Santa, Elf, and other holiday movies.
TiVo was (at least at one point) very good at this. If you would search for content, it would tell you which channels you subscribed to and which apps you could watch it on. But that was limited to one device TiVo.
I think you might be approaching it the wrong way though. I would ignore all of the devices to start and simply start with the content providers. Devices are dependent on content providers and your willingness to subscribe. It doesn't matter that it's on Netflix which works on Roku, Apple TV, Chromecast, Android TV, Amazon Fire Stick, etc. What matters is that you subscribe to Netflix.
For example, when you sign into the app, you put in your location. You are then given a list of content providers to choose from to be included in your search, that way it's catered to your subscriptions. You could also include a checkbox to search all free content providers. And if your search turns up no results, then you could click a link that shows which content providers you are not subscribed to that offer it. After you see that Hulu Plus has a few things you've searched for, you've solved your revenue stream model, by taking a cut of the subscriber fee as a referral.
You could also share the search data with content providers so they know what folks are interested in, and where they are losing out to rival providers.
I like it. The only hurdle is going to be getting all content providers to share their libraries.