I was looking for this comment today because I'm adding this code to a layout I'm converting. I noticed that embed doesn't cover iframe so letting you know. .lj_embedcontent seems like a possible alternative too.

Also I came upon:

pre {
white-space: pre-line;
word-wrap: break-word;
}

which forces the line to break and prevent scrollbars. Not sure you'd like it better or that it works in all browsers but figured I could mention it. :)