Change banner to flv on TwentyTen theme

HI there,

I am using the Twenty ten theme

https://videoessentials.co.uk/

I was wandering is there any plugin or way of changing the header.php so that I can insert an flv in place of the header pic

because it uses a custom header uploader …I cant just find the image in the header.php and replace it with an embed code..it kinda difficult

any help would be very much appreciated ??

Ewan