Cedar Waxwings specialize in eating fruit and can survive on fruit alone for several months. They don't regurgitate seeds like other birds; they defecate fruit seeds. You can watch videos of other birds regurgitating seeds. Check out the Varied Thrush regurgitating a seed or a Hermit Thrush regurgitating a laurel pit while taking a bath.
The waxy red appendages on the tips of the secondaries probably serve as a mating function when selecting a mate.
Waxwings with Orange Tail Feathers
Why do some waxwings have orange tail feathers instead of red? If they eat orange honeysuckle berries (instead of the traditional red honeysuckle berries) while their tail feathers are growing, their tail feathers will be orange.