I'm assuming adding a button in the flash object is out of the question, in that case you can position the anchor over the flash object, using "position: absolute" and z-index (optional). Example: http://jsfiddle.net/qbK5Q/ (I haven't used an actual flash object, but it should work with one):
CSS:
a {
display: block;
position: absolute;
width: 100%;
height: 100%;
z-index: 5;
top: 0px;
left: 0px;
background-color: rgba(255,112,0,0.5);
}
.objectContainer {
position: relative;
width: 100px;
}
If it's a flash object, make sure that it has the "wmode" param set to "transparent" or "opaque". The problem with this solution is that the link will cover the flash object making it inaccessible to your mouse cursor (buttons and mouse events inside flash won't be accessible to the user).