This answer is for Windows Vista, Windows 7 and Windows XP.
Logger Pro is set by default to use the installed sample video files when the corresponding Logger Pro files are opened using Open from the File menu. As a result, most users won't ever have to navigate to the videos manually.
Sometimes instructors want to use the sample videos in their own projects. In that case, it is necessary to find that Videos folder. Here's where it is located.
In Logger Pro 188.8.131.52 and newer, there is a shortcut to the location of the movies. Choose Movie from the Insert menu, then choose Sample Movies. The last item in the folder is called "Original Video Files." Choose this shortcut to open the folder. The actual location of the folder is described below.
Starting with Logger Pro 3.8, experiment files and videos are installed in the Windows-standard location for application support files. This is the ProgramData folder, located at the root level of the main hard drive.
The videos for Vista and Windows 7 are found in:
ProgramData\Vernier\Logger Pro 3\Language_Independent\Movies
The videos for XP are found in:
C:\Documents and Settings\All Users\Application Data\Vernier\Logger Pro 3\Language_Independent\Movies
Note that the ProgramData folder is hidden by Windows by default. This means that it is hard to navigate directly to it without the shortcuts. To simplify navigation, you may want to set your Folder Options in Windows Explorer, View tab, to show hidden files, folders and drives.
Also note that the "All Users" folder for XP laptops may have a dot suffix like "All Users.WINDOWS", etc.
see also TIL 2246: Where does Logger Pro store experiment files?