You can use the built in screen capture tools of OS X to "grab" image files from anything you view on your display. The trick would be keeping the dimensions sized identically for each.
Command-Shift-4 turns the cursor into cross-hairs and you just drag to make your selection and release the mouse button to capture. Since this is "freehand" dragging it would be very difficult to make each capture identical in dimensions. It wouldn't matter what those dimensions were as long as the aspect ratio is 4:3 (640X480, 800X600 etc.)
Open the PDF using Preview, "Zoom" the document to get the needed text size and use the "Selection Tool" to make your area. Try as best you can to get exactly half of the page height.
Use the "Crop" tool to isolate your selection and then use the keyboard shortcut Command-Shift-4 to make your screen capture. You want to capture at 4:3 and also select some of the gray background color at the top and bottom so your image will conform to the TV safe area of a DVD.
There are some free software tools like:
http://www.pascal.com/software/freeruler/ that can help you get the same size for each screen capture.
A 30 page PDF would end up with 60 images files and the steps could be very time consuming.
But it would work.
