Your vid-post is 270px wide but your object seems to be 275px wide and therefore makes the element too big in IE6 as it tries to accommodate the extra width.
You could force the issue by hiding the overflow.
border:#a6d26a 1px solid;
margin: 15px 15px 0 0;
padding: 10px 10px 10px 6px;
A better approach would be to make sure that everything actually adds up and avoid the issue altogether