I don't think I've ever seen this but it's simply a combo of two very cool visual fetishes.
Heather Harmon made deepthroating a true art by continuing to go down on her husband's cock until he was finished cumming. Since they were married and did a lot of other scenes, you knew they weren't faking it, you knew what his load looked like, so when he said he was cumming, you had a good idea what was going on down in her throat.
There's also a variant of shooting a creampie where instead of the guy penetrating her super-shallow from missionary to set up a good leak-out afterwards, instead his cock is half or all the way deep inside her, and the camera catches the view of the underside of his cock, which flexes and pulses quite visibly on the underside when he's cumming. It's also common to see his balls pumping/contracting.
I think if a director put these together he'd make a good name for himself. Have the two performers inverted -- in 69 or some other arrangement where you can see the top of her face at the same time you're seeing his cock from underneath. Then have her finish him off with a good deep-throat blowjob that continues uninterrupted until he's finished cumming. No matter how deep she goes, the base of his shaft and balls will be visibly pumping while he's cumming. This would be a hot way to finish a scene in my opinion.