Make sure your files are unzipped (ie, not in .zip format) before uploading. 

Audio

You can upload audio files of less than 2GB in size that are in the following formats:

• .flv
• .asf
• .wmv
• .qt
• .mov
• .mpg
• .avi
• .mp3
• .wav
• .3gp
• .mp4
• .wma
   

 Learn more about Kaltura's video setting recommendations at their external Knowledge Base.