A client wanted to center an embedded video and was disabling rich text in order to add tags around it to center it. Save it and it works, but edit the node and the WYSIWYG would strip the new tags and break the formatting on save. Granted, these are deprecated tags that were being used but it is not the WYSIWYG's place to be enforcing that.
Unchecking Paste from Word button and unchecking all of these and TinyMCE still deletes center or div align="center" tags.
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