Didn't you notice the video plays at higher than normal speed in MPlayer? (and not the audio). Totem Player reports the files are at 100 fps.
In fact the recording mode used in this file is a bit strange.
It's flagged as progressive (and seems to really be) at 50 FPS and some kind of 'pulldown' seems to be applied. It also seems that all frames are repeated and I wasn't able to remove this 'pulldown' during demuxing, but I've not spent much time on that.
Remuxing the file gives strange results.
When remuxing to MKV I need to specify 25 FPS as the frame rate for a proper playback. In this case the file is playing fine in any player without artifacts even in VLC. However if I specify a 50 FPS frame rate like the original file then the video is playing too fast at twice the speed.
Remuxing to MP4 leads to a complete disaster, whatever frame rate is used 25 or 50, the file is just unplayable in any player, image is stuck and/or showing a lot of artifacts.
So I'm not sure about what is going on there. I think we need a H264 specialist for a deeper analysis of the original file.