Once initialized then we can seek to any point and it will behave just fine.
This issue can happen when the FLV encoded was in H264. This format has a limitation in that unless intialized from beginning, it doesn't render video (and audio) frames. If you share it after it's been recently shared, it is not initialized from beginning. Instead, it tries to play from the last cue point, which causes this issue.
The issue is not present in VP6 encoded FLV files.