The Hooded Warbler male is an exceedingly good-looking bird, with a sweet and easily-recognized song. That is good, because it is hard to get a look at a male Hooded Warbler. They favor dense foliage near the ground in lush forests, from southern bottomlands to Appalachian cove forests. It is the First Category songs, such as this one, repeated without variety, that are easiest to recognize. They signify that he is looking for a mate. That doesn't mean he doesn't have one. Mated males of many species are willing to have a second mate, if they can get away with it.
Second Category songs of the Hooded Warbler are more complex, and a male will have more than one type. That's when the identification headaches begin, as the common Hooded may begin to sound something like the uncommon Swainson's on the one hand, or the spruce-loving Magnolia on the other. Always be careful with warblers.