The Blancos keeper has talked about claims that his side's rivals compiled a tape of Portugal defender Pepe's fouls against them, expressing shock at their alleged actions
The Portuguese star stoked accusations between the clubs recently when he criticised Blaugrana players by saying that they went down theatrically under challenges in the last Clasico and Casillas admitted he was shocked to hear of the news.
"I'm surprised that Barca would make those videos," Casillas was quoted as saying by Marca. "It's normal for them to make them to analyse an opponent, but I don't think this type of video is like Barca."
The 142-capped Spain international also discussed recent claims that his side is interested in signing Radamel Falcao, who plays for Los Blancos' city-rivals, Atletico Madrid.
He added: "He's a great forward, but they're just rumours. He showed that at Porto and Atletico as well as now.
"It's just part of football. Falcao can't really help us this season.
"The ones I think about are [[Gonzalo] Higuain, [Karim] Benzema and [Alvaro] Morata. It's not up to me to decide which players Real Madrid should sign."