"It allows you to convert your regular PC video files (avi, mpeg, etc) into the proper video format that your mobile or fixed video device understands. Each version is tailored specifically to the device in question."
This is a suite of applications specifically tuned to the device you want to create video for. So there is a seperate download for each application depending on your device.
This covers the IPOD, IPhone, PSP, XBox 360, Tivo, and PMP.
For more advanced options and in many cases better quality results, check out my post for MPLAYER and the MeWiG GUI (some PC skill required)