I have been invistigating its features and found it extremely user friendly. It is totally differnt from YouTube. The homepage is pretty simple and it has nothing but a search box where you can type your query.. When you type in a search term , YouTube Instant pulls in the most popular YouTube video for that word and starts playing it immediately. It also shows the next 5 videos just below the one which is playing.
Head over to YouTube Instant and give it a shot.
There is also Instant Search for Images website and Instant Maps, both of which impliment the instant search technology.