Social Security plays a vital role in giving millions of retirees the money they need to pay their living expenses. But the program is so complicated that many fear they'll make a key mistake that will hurt their financial prospects for the rest of their lives.

In the following segment from their video guide to investment planning, Motley Fool director of investment planning Dan Caplinger talks with Fool markets/IP bureau chief Mike Klesta about the complexities of Social Security and how to get to the root of the problem with the program. Dan notes that even single retirees have to weigh complex decisions about when to take benefits and how much they'll receive, forcing them to guess at their life expectancies in order to make rational choices. For those with families, the interplay of spousal and survivors' benefits makes Social Security even more complicated. But the key to keeping Social Security simple is to have other assets at your disposal to help supplement your monthly benefits. That way, you'll have the flexibility to consider beneficial strategies that others can't afford to use.