I've got a question about FNIT too.
When they first get up to their knees and Jack grabs Ennis's jacket, there's a brief pause before Jack goes to take his jacket off. He seems to be looking deep into Ennis's eyes and holding on to Ennis with his right hand, but what does he do with his left? It appears to me that he takes Ennis's right hand and, presumably, puts it on his crotch to leave Ennis in no doubt about what he wants. Does anyone else see this? Or does anyone have another explanation for what is happening during that pause?
i've always thought that Jack puts Ennis's hand on his crotch, but I did notice that, as others have said, that his hand didn't seem to be in quite the right place, but I put that down to Jake, when they were filming it, thinking that it was near enough to give the impression Ennis's hand was on Jack's crotch

(and, in fairness to him, he can't have imagined that people would be analysing it in such minute detail! :-[ :-[ :-[)
But, I've just watched it again, and seen it completely different this time: Jack doesn't take Ennis's hand, Ennis's hand is already on Jack's lower arm as a result of their struggle. All Jack does is pull his arm back, with Ennis's hand on it, then (I'm guessing here, cause you can't actually see), places his arm so that it's directly between his groin and Ennis's hand,and starts to pull his arm away. The pause you mention, NoReins, and the way Jack is looking at Ennis,is (imo) Jack daring Ennis to move his hand away. When he doesn't (well, who would?!

), Jack sees it as the 'green light' to go ahead

At that point, Jack pulls his arm away and atarts taking off his jacket, and you see Ennis's arm sort of drop(and his hand presumably landing in Jack's lap!

), as a result of Jack pulling his arm away.