I was able to reproduce this issue in Confluence version 2.7 and 2.6.2. The steps to reproduce is just simply attach a "*.wmv" file and use the following markup to include the file:

!yourwmvfile.wmv!

If you try to view the page source, you will find that the <param name"data" is missing the "=" sign. However, this is working in Confluence 2.6