Actually, existing search engines do a decent job of that already. It shouldn't take anything new. You can already search under "online TV drama," for example, and get lots of hits. Too many, if anything. Each hit typically gives you a portal, on which you use their search technique.
For US TV viewers, popular portals like Hulu, Amazon, or Netflix will give you lots of choice separated by category. And if you know the TV network that creates what you want to watch, they usually give you ways of serarching right on their own web sites, for full length episodes.
Ultimately, this is like anything else you search for on the Internet. It's no more difficult than trying to figure out what restaurant grabs you interest just now.
Gesture control might be a step forward for some people, but it doesn't address the real issue, which is intelligent search. What is truly needed in an advanced television UI isn't just the ability to control the TV without a remote, or to search for content by name. What will really excite consumer interest is something that solves the problem of "I want to watch something right now, but I don't know exactly what."
Heaven help you if you trying to swat a fly or mosquito with the remote in your hand.
On this quote, though, let me TOTALLY disagree:
"They’re on the couch, so a mouse is cumbersome, whereas a flick of the wrist is not."
There is nothing cumbersome about a mouse! Call it "mouse on the couch," if you like. You get yourself a Logitech wireless mouse, hold it next to you on the couch, and it is trivially easy to to point the arrow anywhere on the TV screen. This is the way I've been wtaching most of my TV programs for more than a couple of years now.
And the advantage of this approach is, you won;t look like some certifiable lunatic when you want to switch channels.