Seeking in video failed Operation not permitted, will use first frame

[x-yuri]

$ ffmpegthumbnailer -v
ffmpegthumbnailer version: 2.2.0

$ ffmpegthumbnailer -i 1.mp4 -o 1.mp4.png -c png -s 300 -t 00:00:02
Seeking in video failed Operation not permitted, will use first frame.

$ ffmpeg -ss 00:00:02 -i _/1.mp4 -vframes 1 _/1.mp4.png
<succeeds>

1.mp4.gz

[FlashTang]

The same issue, how to fix ?