From a porn perspective I can't really tell what his tongue is doing when he is eating her doggie style.
Typically most porn scenes now run 25 minutes with at least 10-15 minutes of stupid LPSG interview (whats the biggest cock...) or ridiculous plot build involving someones "step____", best friends wife/gf, or rando pizza delivery guy/ female maid; followed by 5-10 minutes of foreplay dedicated to cock worship, then usually not more than 1.5 minutes of the guy fingering touching and on a good day eating the pussy, five minutes give or take of fucking then finally the dumb ass pulling out whacking off in her face and then one or both of them playing with the spooge if its a creampie.
Hard to say where eating her ass even has time in there.