Playing video backwards (ogg file does not load)

Hello, I am trying to play a video backwards and forwards. As advised on the video library - speed (, I managed to convert the video from a mp4 to ogg file. Now when I try to upload the new file to processing, I am getting this alert " Could not load movie file name.ogg."

I don’t know what the problem is as this is the suggested file format. Does anyone have any suggestions ?

Thank you