I think what Jasun alludes to in his video posting is that there is something maladaptive about gays in society, although he did not put it that way, nor would I guess he would describe it in that terminology.
But, it is what we use the slang term "gaydar" to express. There is a detectable behavioral quirk, and it is not as overt as glancing at a crotch or ass, but it is there. Instead of any one characteristic, it is the composite of several interactive skills and traits, which change from one culture and country to the next. When gaydar is attuned to Norway, it may not pick up the right clues in Myanmar.
We, as like individuals, recognize sameness. It is an evolutionary adaptation that is used in many other situations to help individuals in larger populations.
Whether one buys into a genetic causation model for homosexuality, or one that is driven by interactive development by the individual, the idiosyncratic markers do wind up as evidence, whether they precede the formation of homosexual mentality within the man, or they result after it has formed. The oft-repeated claim that adults can detect homosexuality in young children may or may not be a reality, depending upon whether the markers precede, coexist, or follow same-sex attraction's development..