How To: Quickly look up words in Dictionary app in Mac OS X

In this video, we zoom into a web page of mac related
sites which displays various websites and their links.
The cursor moves over these various titles and stops over
different words, highlighting each word. A small window
pops up displaying the abbreviation,meaning of the word
and the way it is pronounced. Than the page scrolls down
and the cursor moves over each title , highlighting each word.
We see the meaning of each word being displayed in the pop up.
Now we know that this is possible by holding the Command-Control-D keys.