In windows the video files are being shown as thumbnail view by default in windows 7 these thumbnails might make windows explorer slow to load when there are so many video files in a folder.
In such case you can speed up windows explorer to show these files when the folder is opened by turning off the thumbnails shown for these files, follow the procedure below to disable thumbnails beings shown for files.
1. Open Windows Explorer or just open My Computer and then press the alt key on the keyboard and navigate to file menu Tools >> Folders Options as shown in the image below.
2. Under folder options, click View tab and locate the option which says Always Show icons, never thumbnails and check this option as shown in the image below.
3. Click apply button and then ok, Once you check this option you will not see thumbnails for video files and rather it will show icons. However this tip would be helpful in case you identify these video files with their names.