Try this 1
First check the extension of the newly downloaded videos.
Click on Start --> In search box, type control folders and press Enter.
[If you are using Windows XP then type control folders in Run and press Enter]
"Folder Options" will be opened. Click on the "View" tab.
Uncheck the check box "Hide extensions for the known file types" --> Click on
Now compare the extension of old and new video files.
[Note : Later undo the changes you have made by once again going to "Folder
Options" --> Click on "View" tab and click on "Restore Defaults" button --> Click
If the extension seems to be different then try updating your Real Downloader.