Hulu FLV's: How to convert FLV to MP4 losslessly

[OrchestraAndChoir]

I downloaded some Hulu FLV's & tried to mux them into MP4 with Yamb & it asks me to input a Frame Rate but no matter what Frame Rate I try the output MP4 plays out of sync & choppy & Avidemux will not even open the FLV's

[hyc]

I just use ffmpeg.

ffmpeg -i file.flv -vcodec copy -acodec copy file.mp4

But I don't even bother these days because all of my players can read FLV format already.

[OrchestraAndChoir]

Is there any GUI that reads Raw AVC Streamed FLV ?