Wedding fair prices: Go attend a wedding fair and try to negotiate a better rate with the videographers you meet there. My friend managed to get 10 percent off the usual rate, just by haggling with the videographer in person at the fair.
Package deal: Find out if you can get a better deal if you hire the photographer and videographer together. This means that they will also be working together vs. clashing, which is also a bonus for you.
Watch the clock: Many videographers will charge you for the time they spend at your wedding. Try to limit what they're filming, so you'll save money on their shooting fees. You'll also save money on editing since they'll have less raw footage to edit. For example, tell the videographer to only film the ceremony and avoid other parts such as your pre-ceremony prep.
Edit it yourself: Request the raw footage from the videographer and edit it on your own. Take an online class to gain some video editing skills for programs such as Final Cut Pro. Lynda.com is a good site for these types of tutorials. I actually shoot and edit videos on my own, and it's not that hard once you get the hang of it. Or find a video-obsessed pal who will be able to do it for you for cheap or free!