Videos or MP3 won't run in the Activity-Stream

When I drag and drop a video into the stream, it does not play. The player is showing a duration of 1 minute, but no video is playing. The same thing happens with MP3 files!

However, when I drag multiple files (photos and videos) into the stream, they are displayed normally in the overlay and the videos also play without any problems.

What could be the reason for this?

Does your server have ffmpeg setup? If not your audio and video files cannot be processed to ensure they're a web safe codec. Not all video and audio codecs work in browsers. I recommend contacting your host to ensure ffmpeg is setup then supply the ffmpeg path in CB Gallery > Parameters > Media. Without it video and audio uploads are going to be unreliable and you should probably only allow linking them (e.g. from YouTube). The alternative is you'll have to manually process them to be sure they're web safe codecs.

I have installed ffmpeg. I only have no problems when I drag and drop multiple images and videos into the stream together. However, if I only drag in one video, the video does not play. Same with MP3.