http://pourquoipas732.eklablog.com/un-code-a108373422

HTML

<p style="float: left; width: 400px; height: 140px; border: 0px solid grey; overflow: hidden;"><img class="velo2" src="http://.gif" alt="" /></p>

CSS

<style type="text/css"><!--
.velo2{
-webkit-animation:v2 5s linear 0s infinite normal;
-moz-animation:v2 5s linear 0s infinite normal;
-webkit-animation-play-state:running;
-moz-animation-play-state:running;}
.velo2:hover{
-webkit-animation-play-state:paused;
-moz-animation-play-state:paused;}
@-webkit-keyframes v2{
0% { -webkit-transform:translate(400px,0px);}
50% { -webkit-transform:translate(150px,50px);}
100% { -webkit-transform:translate(-100px,0px);}}
@-moz-keyframes v2{
0% { -moz-transform:translate(400px,0px);}
50% { -moz-transform:translate(150px,50px);}
100% { -moz-transform:translate(-100px,0px);}}
--></style>