Adam,
These are very easy to do using the animatte effect. If you have a wide shot of tall buildings and a title needs to appear to “pass behind” a building, you create a shape matching the building to mask the title. Draw a shape and set it to “key out.” If the shot of the buildings moves, then you add a tracker to make the mask move with the building.
Check out Kevin P. McAuliffe’s Avid tutorials here on the Cow. I think he covers the animatte effect in one of the advanced compositing tutorials. (Dont be put off by the word “advanced” — animatte effects are really easy once you do one or two.)
Bill Stephan
Senior Editor/DVD Author
USA Studios
New York City