If you are wanting to ensure that the flash object actually sits as part of the page you will want wmode=”opaque” rather than ‘transparent’.
Adding this attribute is not that straightforward, Rays plugin uses the WP oembed class and a quick glance at that doesn’t reveal a simple approach to adding this attribute and I’m finding the markup construction rather fractured to follow however there appears to be filters that could be used.
I think a shoutout to @r-a-y might be in order as he will probably know how to feed a new attribute to the object tag – if it proves not feasible the only solution I could think of would be to inject the attribute using jQuery but it wouldn’t be the best approach.
i tried to do as you said and it gave me error
“Warning: call_user_func_array() expects parameter 1 to be a valid callback, function ‘my_eombed_wmode’ not found or invalid function name in /home/wp-includes/plugin.php on line 166”