This is called small penis overcompensation. It happens when those dudes with 3.5 inchers become frustrated by their partners lack of enthusiasm. So they pump harder, faster and deeper but often to no avail. Eventually the chump reaches a breaking point. Somewhere in between the 4th and 7th yawn. Funny shit.
This seems to be one of the rare instances where a woman can orgasm with little or no physical stimulation of the genitals. In this particular case, it looks like the deepthroating and/or gagging is what's triggering her orgasm.
Alright so last night I was on that Ask Alice site or some shit and it says the average vagina is only 6 inches deep. So I'm dying to know how the fuck does this guy fit a 2 foot balloon in his wifes pussy?