Cobie Smulders has been a consistent part of the Marvel Cinematic Universe since her debut in the original Avengers film, she’s even one of the few characters who has appeared on both film and television thanks to an appearance on Marvel’s Agents of S.H.I.E.L.D. However, her role in Avengers: Age of Ultron wasn’t very large and considering the volume of characters that Infinity War is going to need to juggle, we’d guess that any role Smulders will have in the new movie probably won’t be too large either.
Of course, since the clip has absolutely zero actual discussion of Avengers: Infinity War, there isn’t even a hint of any actual news.
If standard practice to avoid leaks is taken, that means Smulders probably doesn’t know anything herself about the parts of the movie she’s not in, which would be most of it.