I thought you said you were watching the action? I can't believe it's not entirely obvious how it happens, it's literally the most basic thing to understand.
Here's a reeaaaally basic example for you of what was happening - they place an offer at $13 for say 500 shares. Someone then places a buy order for 1200 shares. The 500 get bought which would leave 700 shares on the bid, but due to the auto reload they instantly sell another say 500 shares leaving 200 shares on offer at $13. Rinse, repeat. That's why the price never goes over $13.
The high speed trading is certainly no secret, regardless it sounds like it's clouding your thinking.
Have a nap if it's all too much.
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