It's a sign that there is a problem with the video file or the player.
Remember there are NO SIGNS these issues will be going away. YOU get to deal with it as best you can. Fixing these files is well discussed and the key word and method I use is TRANSCODING. Sorry, no I can't write a tutorial about this in every reply but it's a known area that folk have to deal with a lot.
I have a couple of .flv files that were recorded from a webcam. I use VLC Player to view my videos. I have Windows Vista on a Dell. The videos themselves are around 2 hours long, but both VLC and Windows say that the video is only half that long. Basically, even once the knob hits the end of the allotted time for the video, it keeps on going to show the rest, but I can't seek to the other half because the seekbar and VLC thinks the video is only half its actual length. Has anyone ever heard of this before?
So basically, under the time elapsed section of the interface, it displays something like "01:45:03/1:19:04" which makes no sense.