I still haven't found a player for my Mac (or Linux laptop) that can run songs/movies at double speed without making everyone sound like chipmunks.
MPlayer can supposedly do it, though I haven't tried.
mplayer -speed 2 -af scaletempo foo.avi
No person may be convicted upon evidence obtained through the use of devices authorized by paragraphs (2) and (3) unless the speed recorded is six or more miles per hour in excess of the legal speed limit. Furthermore, no person may be convicted upon evidence obtained through the use of devices authorized by paragraph (3) in an area where the legal speed limit is less than 55 miles per hour if the speed recorded is less than ten miles per hour in excess of the legal speed limit. This paragraph shall not apply to evidence obtained through the use of devices authorized by paragraph (2) or (3) within a school zone or an active work zone.
Paragraph (2) refers to radar, and paragraph (3) refers to timing a car between two points. Strangely, this doesn't seem to cover a cop pacing you and looking at his speedometer. Also, I think that if you admit to speeding, you can still be convicted regardless of the above.
Disclaimer: "These opinions are my own, though for a small fee they be yours too." -- Dave Haynie