VideoView always produces "Sorry this video cannot be played"

I have a problem with the VideoView, I am not able to make it play any video file, I always get the error message "Sorry this video cannot be played".

Clips are lying in the root of my SD card and the corresponding B4A line is e.g.:

MyVideoView.LoadVideo(File.DirRootExternal, "clip_480_5sec_6mbps_h264.mp4").

Most of these videos run normally when using the default video player.

Note: VideoViews works when streaming a video from the WEB, so I have the problem with the files on the SD card.

The unfiltered LOG output is shown below, I have tried with different files from different sources (MP4 & AVI). I always get the same errror message and the LOG output always looks as below?

url: /mnt/storage/Ben 10 - s1e02. Prehistoria.avi - player_type: AVOS_PLAYER
sysfs_entry_find: display '1' with index: 0 found
sysfs_entry_find: manager 'lcd' with index: 0 found
LayerBuffer::AvosSource::AvosSource
media_player_video_open: stream_start_file() failed
stream error: 1, qual: 0, pos: 0
30|setError: 1001 - 1000
error (1001, 1000)
surface=0x2db250 (id=0)
LayerBuffer::AvosSource:nVisibilityResolved: 224x88 - 800x480 - 3:180
Error (1001,1000)
Error: 1001,1000


Anybody has an idea what error I am encountering here?

Xtra question: why can VideoView not display any video residing in File.DirAssets (there is an error message saying the folder is not supported). Could be useful for instructional videos etc.

Thanks