Convert youtube videos from flv to mp4 using Freecorder

I downloaded many youtube videos in flv format but my Screenplay HD Multimedia Drive (Iomega) does not play or recognise them. I am trying to convert them into mp4 files. I clicked the option of Freecorder, but I can not see the original flv files eventhough I switched to the right folder where they are located. Help me please. Regards, Luis (Barnett Shale)

I'm not sure what kind of conversion Freecorder uses, but Replay Media Catcher can be used to download videos from youtube for free. And it allows to convert youtube videos to mp4 losslessly (see the "MPEG-4 lossless extraction" conversion preset). Not only it is lossless, but also very fast, so I recommend you to try it first.