As of now Google Instant – Search as you type is not supporting Opera, it supports only Chrome v5/6, Firefox v3, Safari v5 for Mac or Internet Explorer v8. So if you are an Opera User like me you can use the Google Instant in opera too. Opera can handle the Instant features but Google is blocking opera users, so what u need to do is to tell Google that you are using Firefox not Opera
1. Open Google
2. Right Click and go to "Edit Site Preferences…"
3. Network Tad
4. Choose "Identify as Firefox" in Browser Identification
5. Click Ok
6. Refresh the page and you are done.
See the video below