Track Matte

Footage from: http://www.blueskyfootage.com/cgi-bin/clipman/page.cgi?p=freeclip;rank=4

The tutorial has a clear explanation on how to create a transparent effect for the title with just 9 simple steps.

Steps:
1. Import footage
2. Drag footage from project panel to "create a new composition" button
3. Use the text tool, type "london eye"
4. Change TrkMat from "none" to "alpha"
5. Select both layers, Layer > pre-compose, rename as "london text"
6. In the effects & presets panel, select "drop shadow", "bevel alpha" and "hue/saturation"
7. Go back to project panel and drag the same footage below the "london text" layer
8. Double-click on the "london text" layer and press "e" on the keyboard
9. Double-click on either one of the following effect to do some adjustments in the effect controls