That gentleman in the clip is not doing a full version of the lat machine straight arm pullover. If he were to sit down, facing away from the machine, his arms would be more in a 180 degree position. Giving the exercise a fuller ROM (including a better stretch) as in a true straight arm pullover. Of course a lying straight or bent arm pullover (DB/BB) will give a much superior stretch and ROM to the upper body. You are not going to isolate the lat's but you will influence then greatly. Along with the muscles around the rib cage, triceps and pec's. Even the abs are called in strongly. A exercise worth doing in any form. Good Luck.