well, the fixed gear element to preventing bike thievery is really only effective if there's a heated pursuit.

for example, in the one video, the guy that steals the rigged bike just takes it and slowly rolls away with it... and figured out in a very controlled manner that the bike was fg.

however, if you were in an urban-ish setting and performed a similar experiment but gave chase the moment after the thief got on the bike then he/she would probably sprint away (getting to a higher speed before realization that coasting isn't an option) as well as make turns to elude pursuers. it's the turns where i'd imagine a thief would most likely attempt to stop pedaling, as well as learn that they cant coast...

then madness would ensue.

and actually spooki, i doubt any legal repurcussion from such an endeavor. hypothetically, if i were to steal a motorcycle yet have no idea how to ride one and consequently bust my ****, no judge would ever rule against the motorcycle owner.... same would go for a bicycle, right?