(it wasn't on youtube in full or in HQ. bah humbug.)
I feel like this whole scene is a fireball, instant representation of Mark and Eduardo's entire relationship. Like, the whole struggle between them and the months of miscommunication and longing just come to a head in this perfect way where you can see every feeling between them rise to the surface.
When you look at Eduardo you see so much anger, and then as he turns to look at Mark the anguish in his voice and the pain in his eyes just scream "You are my best friend, and you’ve just broken my heart, my spirit and my entire career apart, and all I ever did was love you and help you, what did I do to deserve this?" and it's right there in the dialogue that Eduardo is searching for reasons, looking for things he did wrong and for explanations for Mark's behaviour - to work out how long he's been in a one-sided relationship, and the initial reaction is to hate Mark; to feel everything that Eduardo is feeling and project it onto Mark, and onto Sean who is basically the Yoko to their John and Paul.
But then we see Mark and we see how his face transforms from the "You made a bad business deal with your own company" harshness and supposed lack of feeling into this picture of torment and regret and I feel like as Eduardo walks away, Mark finally realises that he’s lost more than he bargained for. I don’t think Mark ever realised that losing his CFO would equal losing his best friend. To him, he was cutting Eduardo out of the company but not out of his life and he didn't understand that Eduardo would see it as anything other than a business deal.
To Mark it was all black and white, Wardo was his best friend and Eduardo was his CFO and he thought that he could have one without the other and in the moment when Eduardo says to him "I’m coming back for everything" its like you see on his face that he finally realises that he’s ruined this relationship with this person that he loves on a level that he wasn't even consciously aware of. You can see him realise what he’s done and you can see it dawn on him, as he spins back around in his chair that even if Eduardo comes back for the entire company, he wont care, because none of it matters if he hasn't got his best friend.
AND THEN SEAN PARKER BUTS IN AND HUGS HIM AND RUINS THE WHOLE FUCKING THING AND MARK GOES BACK TO BEING EMOTIONALLY STUNTED. Fuck you, Sean Parker, I hate you and everything you stand for.