Get an attorney. File a complaint. Inconvenience the guy so that he doesn't do the same to the next rider. Have a mental plan to start capturing video or getting the attention of passers-by. Post the video on utube. Call your local tv news show. Have them show the video on TV.

Sure video might be inadmissible in court but people on the internets talk like EVERYTHING goes to court. It doesn't. Lawyers cost money. It costs the parties incrementally more money (and you get incrementally less if you win) when the attorney has to take something to trial.