I was fortunate enough to join a team of researchers to look for some old Korean War footag at
the National Archives in DC. I felt like I was back in the college days, reasearching for term papers. Although we had a professional researcher on our group, it was no easy feat to search through the archives. Yes, there are reasons why people pay thousands of dollars for these professional researchers who seem to live in the building. But, I'm going to explain some of the details, or quirks, to pull footage from the archive so that you can save some money as well as time, before you hire a professional--which I highly recommend if you have the budget.
First of all, you should familiarize yourself with the online archives search page. It is no mean complete, but it should get you started and give you an idea what's available. Basically, all government footage, army footage, and some donated footage are free. However, there are some old footage that's still under copyrighted from individuals or media companies like Universal. It is your responsbility to get clearances for those copyrighted footage, not the archives.
Once you locate the footage, you should find out what kind of copys are avaiable. Some are dubbed to tapes for your preview at the archives research room. Unfortunately, many are not. There are film decks which you can pull films and watch for preview like the old days. The pull times are limited throughout the day, so you want to prioritize and schedule accordingly.
If there is a digital tape copy, then you can dub from one of the approved venders at the archive. If not, you will have to pay to dub a copy for you AND the archives. The later option is very time-consuming, as the archives hates to lend anything out of their vault. Expect at least four to 12 weeks, depending on their whim. The digital dub will be faster, which you can expect within a couple of days. However, if you can live with VHS quality footage, just to show to your producer or director, you can bring your own camcorder and hook up the machines to dub. You can also bring your own laptop and flatbed scanner to copy documents and pictures.
If you didn't bring your own camcorder, you can signup to rent one of two dub decks that are available. You can only copy to SVHS or VHS tapes. (Yes they will sell you these tapes at the archive.)
All in all, it was really fun and educational experience. We were fortunate enough to find a digital copy that had all the necessary footages in it. However, depending on your subject, it will be much harder and time consuming. I suggest you start your research very early so that you don't have to wait for the archive beaurocracy, even if you are hiring a researcher. If you have the time and live in the proximity of Washington DC, it is a great place to visit and spend some time for your favorite topic. The archive holds some of the great stories that has yet to be told.