No Diff performed on embedded tags

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Do a html diff on a file that contains an embed tag (eg: youtube video)
2. If the new source doesn't have this tag the embed link doesn't show at all
3.

What is the expected output? What do you see instead?

I would expect the embedded tag to render as red as crossed our similar to img 
tag.

What version of the product are you using? On what operating system?
Latest version, OSX

Please provide any additional information below.
This is probably more of an enhancement than a defect

Original issue reported on code.google.com by stephen....@gmail.com on 8 Jul 2011 at 12:07