How do I transfer videos I recorded on my iPhone 4 to my hard drive?
This Apple Support article details how to transfer content to your computer.

http://support.apple.com/kb/HT4083


  Connect the iPhone, iPad, or iPod touch to your computer. iPhoto
  should automatically launch into its import window with your device's
  images and videos listed.
  
  Select the images and videos you would like to import into iPhoto,
  then select the "Import Selected" option.