How to Calculate Total Duration of Multiple Video Clips?

This is what I do to know the length of set of videos:

Step 1: Select all videos whose total length is to be known >> then right-click , go to properties.

Step 2: After clicking properties, another small pop-up window opens with General & Details tabs. Click Details tab.

Voila, there is a property field named length, with the corresponding value of your total video length.

P.S - Works with Windows 7 and 10. May work in windows 8.

Open up the Library pane of Windows Media Player (at least on v10), and then drag and drop the video files.

You should then see the Estimated Time of all the files reflect the sum of all the video and any other media you have sitting in the library pane.

I remember that WinAmp used to tell you the duration of a playlist (which can include videos), but that was probably a dozen versions ago, so your mileage may vary.