Sometimes, it depends on you're computer's speed.
If you think you're PC is good then it might be that you press it to many times, try restarting you're computer or laptop and try agein.
Sometimes application takes time to open espacially ones that are rarely used.
Try watching it on your Windows Media Player. If you can't see it on Windows Media Player, then it is not formatted correctly to view in Windows Live Movie Maker.
You need to download the video first. For that you can use a program or a website (Google it) Then simply open the video with Windows Live Movie Maker
Windows 7 uses Windows Live Movie Maker (and Essentials product). You have to download the 2.6 version of the program if you wish to use it instead of the 'Live' version.
If you have a PC (personal computer) and not a MAC, you already have Windows Movie Maker on it. If you have Windows 7 as your OS (operating system), then you have Windows Live Movie Maker, an Essential product. To find the version of Movie Maker you have, and to open the program, click on the Start Orb and type Windows Movie Maker in the Search bar. The program icon should appear in the list that is generated. Click on the icon to open your Movie Maker.
You can't open a Windows Live Movie Maker Project (wlmp) on Windows XP operating system. So, don't waste your time trying. Windows Live is for Vista and Windows 7 versions only.
You need to download the video first. For that you can use a program or a website (Google it) Then simply open the video with Windows Live Movie Maker
You need to configure your computer to open files from an earlier version Windows Movie Maker.
You can open any version Movie Maker file in Windows Live Movie Maker (Windows 7) as long as you have ALL of the original source files used to create the project available on your hard drive. If the source files are not accessible, then you will find RED X's through the clips on the Time-line.In other words, it is better to Publish (or in the case of Movie Maker 2.1 version - Finish the Movie) before opening it in Windows Live Movie Maker.
Once you have downloaded Windows Movie Maker the easiest way to open it is:> Click Start, All Programs, Windows Movie Maker (icon) from the listIf you can't see an icon for the program;> Click Start, Computer, Local Disk (C:), Program Files, Windows Movie Maker, MOVIEMK (Application)Or,Command Prompt - type in: MOVIEMK.exe
More details on why the program won't open are necessary to answer the question. What version of Windows Movie Maker are you using?
That is not a file format. Undf stands for 'undefined file'. Files used in Windows Movie Maker have to be compatible with the program as well.
Windows Movie Maker is not found in the Documents folder. It is in the Programs folder.To find your Windows Movie Maker:> Click Start, All Programs and Windows Movie Maker (icon) on the top of the listIf you don't see the icon on top of the All Programs list, scroll down to the Windows Movie Maker folder... open it and click on the Application's icon from there.If you don't see the Windows Movie Maker folder in the All programs list, try this:> Open Command Prompt (or Start, Start Search)> Type: MOVIEMK.exe into the space provided and click EnterWindows Movie Maker will appear in the list that is generated by the action.