I think these calls were geared towards duck hunters... You cup your hands over them to get the correct tone, and do a feeding chuckle...
The gentleman blowing the Haint is not doing it correctly... He is just trilling his tongue... As mentioned above, you cup your hands over the call for the correct back-pressure/tone, and do a feeding chuckle into the call.
Say
: "
Digga-Digga-Digga-Digga-Digga"
Here is a call I fashioned that sounds just like the turkey thunder or Haint.... (just click on the black square below):