vave's husband said that the way it was moving the vegetation, it sounded much bigger, and also faster, than a large wild pig. If he's an avid outdoorsman and hunter with a lot of experience in the forest and hunting pigs, I trust his observation.
it sounds like both these men spend a lot of time in the bush for either scientific research or hunting (and do so in some remote locations), so I don't imagine these are men who spook easily. If, with their combined experience, both heard a scream that was unfamiliar to them (which neither could place with a known animal nor identify as a person) + the husband attributed this scream to what he heard moving around (which sounded to him to be larger and faster than a large wild pig)... well... at that point you're running out of options as to what this was.
going by what vave has shared here, we can say this was something that was larger and faster than a wild pig, with a scream (that again, the husband says was not the sound of a pig) which made it obvious to two experienced outdoorsman that it was time for them to leave. Whatever this was, it made them aware of it's presence and I'd say it let them know they were unwanted (and they got the hint).
SeCRETofTheForest you definitely have a point here! Description matches exactly my husband and father in law and what got me freaked out as well from their accounts was not only the odd scream, but the size of whatever was lurking there. In the jungle here we don't have large animals, wild pigs are possibly the largest and don't normally exceed 120-140kgs in the Tropics. Also the fact that not anyone can access this area, makes it very remote... gives me the chills! They have been back in the surroundings forest areas, but not yet where they had that experience. They are talking about going back (again, for scientific reasons), but my husband is still a bit reluctant at this stage. Huh!