Looks like you have extra } in there. Here is what mine looks like....
// ==UserScript==
// @name Player Image Changer for Replays
// @namespace GLB
// @description Updates the background of your existing player icon for replays from transparent to a solid color
// @include
http://goallineblitz.com/game/replay.pl?pbp_id=*// ==/UserScript==
window.setTimeout( function()
{
if(document.getElementById('568680')){
document.getElementById('568680').style.backgroundColor = 'red';
}
if(document.getElementById('602537')){
document.getElementById('602537').style.backgroundColor = 'red';
}
if(document.getElementById('602379')){
document.getElementById('602379').style.backgroundColor = 'red';
}
if(document.getElementById('602620')){
document.getElementById('602620').style.backgroundColor = 'red';
}
if(document.getElementById('630760')){
document.getElementById('630760').style.backgroundColor = 'red';
}
if(document.getElementById('630800')){
document.getElementById('630800').style.backgroundColor = 'red';
}
if(document.getElementById('630828')){
document.getElementById('630828').style.backgroundColor = 'red';
}
if(document.getElementById('637123')){
document.getElementById('637123').style.backgroundColor = 'red';
}
if(document.getElementById('637199')){
document.getElementById('637199').style.backgroundColor = 'red';
}
if(document.getElementById('637093')){
document.getElementById('637093').style.backgroundColor = 'red';
}
if(document.getElementById('637286')){
document.getElementById('637286').style.backgroundColor = 'red';
}
if(document.getElementById('637385')){
document.getElementById('637385').style.backgroundColor = 'red';
}
if(document.getElementById('637431')){
document.getElementById('637431').style.backgroundColor = 'red';
}
if(document.getElementById('637253')){
document.getElementById('637253').style.backgroundColor = 'red';
}
if(document.getElementById('637488')){
document.getElementById('637488').style.backgroundColor = 'red';
}
if(document.getElementById('637323')){
document.getElementById('637323').style.backgroundColor = 'red';
}
}
)