I’ve modified your blend file to make it way longer (so it doesn’t seem to be frantically racing around a maze) and slowed the camera at one point to make it look left and right.
Take a look.
There are two things: First, select the path in object mode and, in the IPO curve editor, select ‘Path’ from the ‘Show IPO Type’ drop down menu. I’ve split the IPO curve by adding keyframes. If two adjacent keyframes are at the same height, the camera’s movement along the path will pause. If the slope between two keyframes is steep, the camera will hustle along quite briskly. (BTW, after you select the path, switch to Edit mode real quick and there you can modify the PathLen value. It starts at 100 by default, but you’ll want to make this longer for longer animations)
Second: select the camera in object mode and select Object in the IPO Curve editor. There you can see the keyframes I added to cause the camera to look left and right when it stopped.
Play around with this and see if it begins to make sense.
camera_path_test_modified.blend (312 KB)