Video format discussion, preferred format/container for upload?

I prefer Matroska (mkv) smallest possible filesize, but not very easy for editing later.
Only a player will support it, mplayer, VLC or MPC are three of them.
I didn't found any mkv-file in the DL section, not only one.

Many young people today are using smartphones for internet, I know a handful using iphone(4).
To be compatible to those mp4 container is the format of choice, perhaps with reencoding into h.264 for smaller filesize.
Most videoplayers of today will support.
I found some mp4 in the DL section.

MPEG is an almost widely used container, there exist some editors and most player will support it.
I found several mpegs in DL section.

Obviously AVI is the most common used container, nearly every player will support it (if the used codec is installed) and the most editors are availble.
Most files in DL section are AVIs.

Windows specific formats/containers like WMV or ASF are supported by me.