For the first egg (Jack Black's scene) go into the Scene Selection menu on disc one, and head to the final page where you'll find the real Council of Elrond scene. Highlight that scene and press "down" to find an image of the Ring. Press enter to view the entire clip from MTV complete with an introduction from Peter Jackson
The second egg can be found on disc two, and is the awesome four-minute "Fan Preview" of The Two Towers that was shown at the end of The Fellowship of the Ring this past March as it was on the way out of the theaters.
To watch this awesome trailer, go to the Scene Selection menu and navigate your way to the final page where you'll find the chapter with the Fan Club Credits. Move the cursor to the numbers on the far right of the screen, and when it's on "48" press down to make an image of the Two Towers appear. Press enter to view the trailer in full anamorphic widescreen and Dolby Digital 5.1 audio.