Description:
When seeking in an ASF/WMV video in Totem (gstreamer, not xine), I got the following error:
An error occurred
Internal data stream error.
Watching the video without seeking works normally, multiple pause/play actions work fine too.

Running totem in a terminal shows:
** Message: Error: Internal data stream error.
gstasfdemux.c(1372): gst_asf_demux_loop (): /GstPlayBin:play/GstDecodeBin:decodebin0/GstASFDemux:asfdemux0:
streaming stopped, reason wrong-state

Packages versions:
$ pacman -Qs gstreamer|grep local
local/gstreamer0.10 0.10.21-2
local/gstreamer0.10-bad 0.10.8-1
local/gstreamer0.10-bad-plugins 0.10.8-1 (gstreamer0.10-plugins)
local/gstreamer0.10-base 0.10.21-1
local/gstreamer0.10-base-plugins 0.10.21-1 (gstreamer0.10-plugins)
local/gstreamer0.10-ffmpeg 0.10.5-1 (gstreamer0.10-plugins)
local/gstreamer0.10-good 0.10.10-1
local/gstreamer0.10-good-plugins 0.10.10-1 (gstreamer0.10-plugins)
local/gstreamer0.10-pitfdll 0.9.1.1-2 (gstreamer0.10-plugins)
local/gstreamer0.10-python 0.10.13-2
local/gstreamer0.10-ugly 0.10.9-1
local/gstreamer0.10-ugly-plugins 0.10.9-1 (gstreamer0.10-plugins)
local/totem 2.24.3-1 (gnome-extra)

$ pacman -Q ffmpeg
ffmpeg 20080715-3

Steps to reproduce:
wget http://www.poliziadistato.it/pds/download/cineteca/video/scientifica.wmv
totem scientifica.wmv
Reposition the seek bar and watch the error box and the error message in the terminal window.