We can't see because it's a normal and not a porno movie but I can suppose that big penis of the "son" ejaculates, too quickly, a big amount of sperm deep inside "mother""s hairy pussy in the second scene. And that, in the third scene (in the bed), "son" can wait sufficient time before to ejaculate a big amount of sperm deep inside "mother""s hairy pussy as "mother" "ejaculates" big amount of vaginal juice all around "son"'s penis. So "mother" & "son" have a simultaneous orgasm !