IM Valeri Lilov describes the move 4...Bc5 as a very logical continuation, putting immediate pressure on the knight on d4 and requiring from White a concrete handling of the position. The video presents the basic theory both sides need to know about the Scotch with 4...Bc5.
Below you can have a closer look at the variations presented in the video by replaying the moves on the board. You can also introduce your own moves and analyse them with the help of the engine.