When I loaded my new Leopard imovie imported all my previous movies from my Canon that were in iphoto but none of my Sony movies.
Are these videos compatible or incompatible with iMovie '08? If compatible, were they stored in an iPhoto "Event" or an iPhoto "Folder?" If in an "Event", try creating a new "folder" for the videos and drag one to the folder as a test. Close iMovie '08 if it is still open and then reopen it. If this was your problem, iMovie '08 will now proceed to "thumbnail" the test video your dragged to the folder and the video will appear under "iPhoto" heading of the iMovie '08 "Event Library." If the videos are incompatible, they will have to be converted for import to iMovie '08 before getting them to show up/import.