Googling led me to this page where the author had the same problem, and they found a solution in Safari Bookmarks Extractor. I can't test that it still works with version changes in both, but it probably does. Once you have your extracted bookmarks, you just use Manage Bookmarks -> File -> Import -> From File.
Oh-kay -- I'd say this isn't quite ready for primetime (as it were). Looks like they take a closed captioning feed as the text source, then map hits in that to the "accompanying" video scene. Which seems pretty clever.