Which file format are they?
Animations are developed in java applets and running from html page.
Applets are, to my knowledge, filtered out by the html editors just like javascript and other potentially nasty tools. This is a standard anti-cracker security measure to help keep students honest.
When I need to add things Moodle doesn't want me to add, like a google site search using javascript, I turn off the wysiwyg editor and paste in my html. You control the editor in admin/configuration/editor settings.