Problems this idea has:
1) How to attach it? Anything permanent (glue) is not ideal, as cords break, and if the cord on this thing breaks then you've got to try to pry it off. Velcro just loses its sticking power after too many uses, and it's likely to reach that limit quickly being tugged on in a pocket as one's leg moves.
2) Where to find a camera with that form factor? Most have nice long cords of their own.