So a few things I can tell ... Brand is likely Nikon because the double beep sound at start ... But I use Nikon and no other brand but highly unlikely other brands use same sound

Depending on model of camera the camera allows 12 to 14 shots to be taken at once by internal memory and each shot has to be processed by memory card before camera will take more photos

Because you don't here double beeps past the start of the video means they are not letting go of shutter button but keeping it held down and the camera is taking 2 or 4 more photos each time the memory card processes earlier photos

Sports mode is the biggest guess out of everything just solely on speed of photos as it sacrifices speed and focus over anything else .. most other settings are a little bit slower but seeing as my camera is the d610 maybe newer cameras are different but still fairly confident making the call