If you have loads of videos that you need to convert so they’re no longer corrupted, then you can use various VLC Codecs to convert videos as desired.
Codecs are programs that shrink large video files while ensuring minimal loss of quality. Try using VLC Media Player (www.videolan.org) to convert them. Open its Media menu, then select Convert/Save and click the Add button. Choose the video file, then click the Convert/Save button and choose a codec from the Profile dropdown menu (see screenshot). Select a folder to save the file to, then click Start to convert and hopefully repair the video.