The video is about the LMS algorithm, which stands for the Least Mean Square algorithm. The algorithm is used to train adaptive neurons, specifically the Adaline neuron, which was developed by the speaker and his first doctoral student, Ted Hoff, in 1960. The Adaline neuron is manually trained using knobs and switches, and its objective is to minimize the error, which is the difference between the desired response and the actual response. The LMS algorithm updates the weight vector based on the error, with positive errors resulting in the addition of the input pattern to the weight vector, and negative errors resulting in the subtraction of the input pattern. The speaker demonstrates the use of the Adaline neuron using various input patterns and shows how the weights are adjusted to obtain the desired response. The speaker also introduces another version of the Adaline neuron, the MR Adaline, which uses electroplating to adjust the resistance of resistor elements and simulate the weights of the Adaline neuron.