Is taking a vitamin supplement with over 1000% dv for a vitamin have a benefit? doesn't excess of some vitamins get expelled in urine?

Maybe: The fat soluble vitamins, A, E, D & K accumulate in your body & pose a greater risk for toxicity when consumed in excess than water-soluble vitamins. The B vitamins and vitamin C are water soluble and any excess is generally excreted in your urine. The late Linus Pauling, a Nobel Prize winner, reported there were many health benefits benefits of large doses of vitamin C.

In many cases yes!: The RDI or DV of a vitamin has nothing to do with the optimal amount for health but only the amount of the vitamin that prevents gross deficiency symptoms in most people. For example, the RDI of Vitamin E is only 30 IU but many authorities believe that 400-800 iu/day is optimal. The RDI for D is 600 iu for most but most adults need at least 6000 iu/day for optimal health! See my comment: