And as another illustration to my previous reply, here’s another observational study, in various natural settings, of the male’s natural ejaculation behaviour. (To skip intro, go to 0:31 ; touch here if you cannot see the video ;excerpts from various straight vids, focussed on the male action.)
Fucking a Tenga Flip, an internal view. Showing a Tenga Flip working its magic on a guy’s wand, complete with devout moans and internal ejaculation (and loud music too). (Touch here if you cannot see the video.)