I just re-did the test and now my score is 20.479%.
However, my geekhood extends into areas not covered by the questionnaire. For example I know that the pixel aspect ratio for PAL-DV is officially 128:117, rather than the 16:15 commonly used by some editing software .... and that therefore only the central 702 x 576 of the 720 x 576 frame represents a 4:3 scene. I also know the technical reason why 704 x 576 or 352 x 288, etc are used as an approximation (instead of 702) in some circumstances.
They also didn't go into enough detail about artificial languages and maps. As a kid, my favourite thing to do when I went on holiday with my family was to stay indoors while they went to the beach, and a) invent a language with absurdly complicated inflexion systems — and then invent irregular nouns and verbs. b) draw exceedingly large streetmaps of imaginary cities, with many hundreds of streets with thoughtfully chosen names. I would then keep taping more and more sheets of paper around the edges and "expand" the city. Those things alone gave me tremendous mental pleasure.