To install this application on your iPhone, you must know how to jail-break the iPhone and install the software needed. The following sites provides excellent information on this topic.
http://www.hacktheiphone.com/
http://hackint0sh.org/forum/showthread.php?t=3284

Install Method 1: installer.app method
Please add iPhone Video Recorder source http://www.iphone-recorder.com/install2 to your iPhone installer.
How-To: Add third-party sources to your iPhone's Installer.app

iPhone Video Recorder Source: http://www.iphone-recorder.com/install2

After refresh your installer source, you will find iPhone Video Recorder in Multimedia category, install it.

Install Method 2: PXL package method
Download the PXL package below and use with Breezy (mac), iBrickr (windows) or using the PXL MobileSafari plug in to install it.

Download iphonevideorecorder.pxl (510KB)

Supports firmware 1.0.x, 1.1.x (All known versions) iPhone.