Like you, I don't watch the ASI during takeoff ... but I would be surprised to learn that one could safely take off with an IAS of less than the aircraft's stall speed, unless there was a "skyhook" involved
Ground effect mate thats how... Same as landing - if you were to be looking at the ASI at the point of a perfect 3 pointer it would read less than 35mph ... ground effect... STOL pilots friend!
Kingy