There is a filter in VirtueMart, which cuts the object and the embed html tags.
A modification should be completed in the administrator/components/com_virtuemart/classes/phpInputFilter/class.inputfilter.php file.
In order to embed YouTube video and other Flash files in your VirtueMart product description area you should remove the object and the embed items from the following array:
var $tagBlacklist = array(‘applet’, ‘body’, ‘bgsound’, ‘base’, ‘basefont’, ’embed’, ‘frame’, ‘frameset’, ‘head’, ‘html’, ‘id’, ‘iframe’, ‘ilayer’, ‘layer’, ‘link’, ‘meta’, ‘name’, ‘object’, ‘script’, ‘style’, ‘title’, ‘xml’);
The new array will be:
var $tagBlacklist = array(‘applet’, ‘body’, ‘bgsound’, ‘base’, ‘basefont’, ‘frame’, ‘frameset’, ‘head’, ‘html’, ‘id’, ‘iframe’, ‘ilayer’, ‘layer’, ‘link’, ‘meta’, ‘name’, ‘script’, ‘style’, ‘title’, ‘xml’);