While I liked the idea of Zemo manipulating the whole situation for his own vengeance (a recurrent theme of the film), I found it a bit hard to believe that (as he's portrayed in the film) an ordinary officer of the Sokovian army with no connections to Hydra (unless I missed something) managed to find out about the existence of the Winter Soldier program and was able to know how to follow the tracks to more information on it. Perhaps my second viewing will clarify this issue.
Zemo explains that in his first appearance - he got the info from the files that Black Widow released to the public in Winter Soldier (although he says they were encrypted, which to me defeats the purpose of releasing them to the public, but hey...).
Saw the film yesterday - really enjoyed it. All of the character beats felt natural and entirely in keeping with the arcs these people have taken. Both sides were credible and you could see why they felt as they did. Was entirely wrong-footed by the final twist of showing Tony the tape and Cap knowing, and I liked that Cap and Tony remain divided at the end. Thought Spidey and Black Panther had excellent debuts, and am looking forward to their solo movies a lot now. Also wondering how this new status quo will affect the Ant-Man sequel, as Scott is now a fugitive (poor move by Ross to imprison two men with families in a secret, unvisitable prison...).