If a video is embedded using the universal embed code or the image embed code, it can sometimes fail in IE. This happens when the embed tag is included inside a <span> tag, either directly or nested within other tags. This happens because according to the HTML specifications, it is illegal to put block-level tags inside an inline element such as a <span>. Most browsers ignore this, and even IE ignores it for the most part. However, when modifying the page using javascript, IE will sometimes refuse to break this rule, and this is what causes the problem.

The solution is to not use <span> tags around the embed code. Usually, replacing it with a <div> tag is a simple solution.