As for the v8, if you insert a animated gif file on the header this is merged together with the header. The best way is to convert it as SWF, flash file. 

There are many free tools on the net that permits you to converto from gif to swf. 

Thanks ,I did find the converter, but when I convert the file ,I can't find it ?????

thanks , i'll try

why don't you add option to use animated gif instead of swf.

Animated gif are quite an old format that is becoming less used over the Internet (it supports only 256 colors)... anyway I'll save this suggestion as an Idea