Pretty simple synopsis, it's clear to be the beginning of Stark's and Cap's disagreements.
**Not really spoilers, but if you just don't want to know what's in the scene****
Cap and Stark are chopping up some wood at a house that seems to be out in the middle of nowhere, in the country somewhere. Given who their villain is, makes sense to be somewhere like that.
Stark: (says something about going to Thor for answers, hard to make out in the video.)
Cap: Sometimes my teammates don't tell me things, I was kind of hoping Thor would be the exception.
Stark: Yeah, give him time, we don't know what the Maximoff(?) kid showed him yet.
Cap: I don't know what she showed you. I just know it made you do something stupid. (Chops another piece) Earth's Mightiest Heroes, pulled us apart like cotton candy.
Stark: Seems like you walked away all right.
Cap: (Chops a piece) Is that a problem?
Stark: I don't trust a guy without a dark side. (Chops a piece) Call me old fashioned.
Cap: Well let's just say you haven't seen it yet.
Stark: (Again slightly marbled)... and I did the research....
Cap: That would affect the team...
Stark: That would end the team! Isn't that the mission? Isn't that the why we fight, so we can end the fight, so we get to go home?!
(Cap rips apart a piece of wood with his bare hands in anger)
Cap: Every time someone tries to win a war before it starts, innocent people die. Every time.
(Scene ends with the two staring silently at each other.)
***End scene***