This video explains the differences between linear and nonlinear ordinary differential equations and how to identify whether a differential equation is linear or nonlinear.
It explains that for it to be linear, the degree of the dependent variable and its derivatives must be 1 and that there must be no product between the dependent variable and its derivatives.
It uses a number of examples of differential equations and compares to the standard linear form of differential equation and explains why each is either a linear or nonlinear differential equation.