FLV video freezes while playing

[NeonFlash]

I have used Stream Transport to capture FLV videos from a site.

Now, the problem is, some of these videos (especially the High Definition Ones), do not play properly. I am using VLC Media Player for playing these FLV videos. They play properly for the first 9 to 10 seconds. After that the video plays very slowly. I mean, the frames appear one by one, almost like a slideshow.

I have a high end graphics card (ATI Radeon HD 5870), so it should not be related to the hardware acceleration issue. Also, I am able to play other High Definition videos on my machine without any issues.

The playback behavior of FLV videos I have downloaded from the site are of 3 types:

1. Videos which play properly without any issues at all.
2. Videos which play properly for 10 seconds or so, then freeze, then skips 10 seconds and starts playing properly again, then freezes and plays normally again.
3. Videos which play properly for first 10 to 20 seconds, after which they will play very slowly, the frames move slowly, one by one.

How can I fix this?

I can provide the details for the FLV videos for each of the above categories (stream encoding info, bitrate) using the output generated by ffmpeg.

I even tried converting the FLV videos to AVI using ffmpeg with the following command line, however, same issue:

ffmpeg -i flash.flv video.avi

I would be really glad if someone can help me solve this issue.

Thanks.