zip file: This is a "zip" file (a compressed data file), and you will need a data compression utility such as WinZip to open it. Download the free utility - click here.
docx file: You need the Microsoft Word program, a free Microsoft Word viewer, or a program that can import Word files in order to view this file. To learn more about the free Microsoft Word Viewer, visit the the Microsoft Office Compatibility Pack.
The MP4 file type is primarily associated with 'MPEG-4'. Play MP4 files with various players such as QuickTime or RealPlayer.