Conjecture.
No doubt there are some very good athletes in rugby, but the point stands that none of those clips are particularly impressive feats of strength in the wider context of elite human athletic ability.
A guy like Tuilagi is doubtlessly a freak, but to be "world class" in the bench he would need to be benching over 300kg at his bodyweight.
Bearing in mind that the "evidence" that he can rep (see that there is no mention of how many - certainly nothing specifically about 5) 250kg is that Austin Healey said so in an article for the mirror.
You hear a lot of what is quite frankly ********, bandied around about "so and so runs a 4.2 second 40m" time and very little solid evidence to support it.
Particularly when you get someone like Carlin Isles come in and demonstrate just how fast a lot of top wingers claim to be - it's plain to see they aren't anywhere near as quick as they claim.