Is that possible to make mirrored?

You can do it using a CSS3 3D transformation.

#videoElement
{
    transform: rotateY(180deg);
    -webkit-transform:rotateY(180deg); /* Safari and Chrome */
    -moz-transform:rotateY(180deg); /* Firefox */
}

This will rotate it 180 degrees around its Y axis (so you’re now looking at it from behind) which gives the same appearance as being mirrored.

Example at http://jsfiddle.net/DuT9U/1/