In this video, the presenter demonstrates proper form for three popular exercises: squats, lunges, and deadlifts, focusing on common mistakes and corrections. For squats, the presenter emphasizes avoiding inward buckling of the knees and shifting weight forward. Proper technique includes keeping the chest lifted, pressing the knees outward, and distributing weight into the heels. In lunges, similar principles apply; the chest should remain upright, weight should be in the heel of the front foot, and the knee should stay behind the front toe. Next, the presenter covers the stiff-legged deadlift, warning against using incorrect form which can lead to lower back discomfort. Key corrections involve maintaining a neutral spine and gaze, rolling the shoulders back, and keeping the knees slightly bent. The focus is on correct posture and weight distribution to prevent injury and maximize the effectiveness of each exercise.