flvdemux: seek in push mode makes it start from beginning

Submitted by Kyrylo V. Polezhaiev

Link to original bug (#680087)

Description

I am using Fedora 17, GStreamer 0.10.36 and Good plugins 0.10.31-6.
When trying to seek FLV file via HTTP, get following error from flvdemux:
"failed to find an index, seeking back to beginning".
To reproduce, please open any GStreamer player with GST_DEBUG=flvdemux:3 and open FLV file located in HTTP server.

Version: 1.x