[Plugin: wordTube] mp3 not playing

I have a similar issue as described here: https://www.ads-software.com/support/topic/268891?replies=2

I am using the latest WordPress and the latest wordtube.

But my problem is worse, since the mp3-files are not played. When I click on the play butten, it seems to be loading, but then nothing happens.
When I was looking through the web, I found some similar error report, but always withough a solution.