In the video, a man is working on a car engine. He is using a wrench to loosen the bolts on the alternator. Once the bolts are loose, he removes the alternator from the engine. The man then proceeds to replace the alternator with a new one. He carefully aligns the new alternator with the engine and tightens the bolts with the wrench to secure it in place. The man takes his time to ensure that the alternator is properly installed and that all the bolts are tightened securely. The video provides a clear view of the engine and the alternator, allowing the viewer to see the process in detail.