I don’t know anything about “Campayo’s Photographic Speed Reading technique”. But it is very much possible to create/visualize the main points of a paragraph/chapter of a book and review them(like ‘mental video’).
I use this ‘convert main points of a page’ idea into images and I then put those images in the locations of a Mamory Palace. This is so effective to both comprehend and memorize the main contents of a book! Without converting the ‘texts to images’ and linking the images,I simply cannot remember the contents of a book well.
I think,it is possible to visualize 4-6 words at a time. Ramon Campayo’s claim is not completely baseless,I think! Mr. Harry Lorayne also suggests something like this in his books.