CB flv speex - what player?

[havedenu]

So I don't know if this is a problem with downloaded videos from CB or a general problem so I posted it in this forum.

Downloaded several videos from CB with rtmpdump and they have speex codec for audio.
Now I wonder what player could play them without converting?
My standard player is KMPlayer which plays the flv video perfectly and can jump in the video file. The problem is that I have no sound.
I tried vlc (they don't really care about speex as it seems) and mplayer, where I have sound but the file is not seekable.

Does either mplayer or KMplayer work when I install some codec pack - any experiences? What player do you use?

I know I can just convert the videos via ffmpeg -i x.flv -vcodec copy -acodec libmp3lame -ar 44100 y.flv but I ofc would prefer to just play it.

Thank you