That's a captain trying to talk to their pushback crew on the intercom. Obviously he has no idea how to use his radio selector switch.
My guess is it was a mechanic not a member of the flight crew.
When I worked the ramp in SYR we used to tow planes every night with a contract maintenance person riding the breaks. He would flash the nosewheel taxi light to let us know when the breaks were on/off. I suppose one could
use the pushback intercom system if one knew how to work the comms. I guess that wasn't the case here.
By the way Cessna157, I'm guessing you're a first officer. I'm sure a captain would have posted "..that's an F/O trying to talk to their pushback crew."