There was definitely a breeze that day - you could hear it in the microphone - but the Helio specs indicate a minimum speed of 28 mph (!) Not advisable to fly that slow, but it’s crazy anyone can keep a plane in the air at that speed.
Not even Cubs or Huskys or other back country planes fly that slow. My guess is he was doing somewhere around 40 on airspeed, maybe low 30s over the ground.
Those slats and the length along the trailing edge of the regular flaps is really something else.