I tried before and found no response.

As I for my videos. Avi. Mpg, and. Mp4 can be downloaded by the system? There must not be displayed in the browser, but only that they are listed for downwload.

zenphoto supports the following video formats 'flv','3gp','mov'. You can convert your files to one of these formats.

Movies on the web primarily have to be converted to flv for best viewing, and this is the format Zenphoto supports best. Quicktime (mov) and 3gp (from some cell phones) are also supported, but FLV works best.

This encoder works great for me: http://www.rivavx.com/?encoder

If you are Mac user I recommend http://ffmpegx.com/

and to not forget linux..you can do in a terminal;
mencoder $file -o $file.flv -vf scale=520:390 -of lavf -oac mp3lame -lameopts abr:br=56 -ovc lavc -lavcopts vcodec=flv:vbitrate=900:mbd=2:mv0:trell:v4mv:cbp:last_pred=3 -srate 22050
and
ffmpeg -i $file -f mjpeg -t 0.001 -ss 00:00:05 $file.jpg
to extract a frame to use as thumb

tks for help!

but i only need that apears one image, like videoDefault.png, and then, when someone click on the image, apears to download link for the avis, mp4s, movs...

Not display on browser. I need preserve the video quality. I tink that have this feature default on zenphoto core, but dont have enconter some FAQ information about this.

No, we don't have such a download link for movies (only for images), all supported movie formats are displayed in the browser, all others simply do not work.
But you can add a link to the image description field in the admin manually.

Ok.

But, if are TOO MUCH videos and photos?

Is too hard to make a hack that take videoDefault.png or image of same name of video and make the links for download on galery when you click on the image?

Here is other tread on http://www.zenphoto.org/support/topic.php?id=2022&replies=3. This tread works?

That thread talks on how to create a video specific thumbnail for a video. It works, but has nothing to do with creating a download link.