I have a couple of AVI videos and I want to convert them to MP4 but all converters have "small and short" watermarks the size of the whole screen and are shown for more than 4/5 of the movie's length

Hi. Have You tried the VLC media player (http://www.videolan.org/vlc/) ? I recommend it- it's free and functions pretty well, since I got it I never needed to install any codecs or different software.
I hope this works for You.

Why are you looking to convert the files? Are they for use on a portable media device? Also, what type of encoding are the AVI files you are attempting to convert.

I would start by checking SourceForge.net: Download and Develop Open Source Software for Free (http://www.sourceforge.net) for some conversion software.

Why are you looking to convert the files? Are they for use on a portable media device? Also, what type of encoding are the AVI files you are attempting to convert.

I would start by checking SourceForge.net: Download and Develop Open Source Software for Free (http://www.sourceforge.net) for some conversion software.

Yes for my iPod nano

I don't want a player but a converter so I can see it on my iPod nano and it can't play AVI.

FREE FLV CONVERTER (free from cnet.com) will convert flv files directly to mp4 with no watermark, just in case you had gone from flv to avi first.