Unlike the first one, this app will be beneficial for most Android users. Like with iPhone, Android lacks Flash capabilities, and thus handles YouTube by using a stand-alone player app. When a user clicks a YouTube link, the YouTube application fires up and immediately begins playing the video, full-screen. (If you can really call a phone's display "full-screen.") This means you don't have the luxury of seeing any information about the video before you play it.
My app solves this problem rather handily. Instead of sending YouTube links immediately to the YouTube app, they go through my app first, causing a popup with title, description and thumbnail image. And then a button at the bottom which will send the video to the YouTube app if you really want to watch it. If not, just hit back or the 'ignore' button. No more Rickrolls.
Like with my first app, this one is available both as a paid app and as a free app for the cheapskates. My logic is that the more people actually get benefit from an app, the more likely they'll EVENTUALLY be to throw me some cash. If they have to pay upfront, very few people will even try it.
(For the interested, this logic has proven to be very, very flawed; after 48 hours in the Marketplace, the free version of youtube Sleuth has well over 1,000 users. The $0.99 version has 9, and one of those was D. (Unlike on iPhone, you can "refund" apps you don't like within 24 hours of purchase -- but the catch is you can only do it once. If you install it again you are stuck with it. I was testing it and accidentally "bought" it from myself using D's phone one too many times.)