There's already a thread on Jack S. Martin, the old guy who worked for Guy Banister in New Orleans when LHO was there at 544 Camp Street.
But there's another Jack Martin, namely, Jack T. Martin (a.k.a. John T. Martin) who made a home movie showing his airplane flight to Dallas, then General Walker's shot-up home in Dallas; then his airplane flight to New Orleans; and finally Lee Harvey Oswald handing out FPCC fliers on Canal Street.
One of the last things that Gary Mack did as director of the 6th Floor Museum in Dallas, there in 2015, was to post Jack T. Martin's home movie on the Internet