i thought rttp had this at one point to prevent hotlinks like photobucket does when bandwidth exceeds... it switches it with a default image... how is it done?

no I didn't. I have one that shows if the image is missing (using an error page script). do you have access to htaccess?

on my computer yes... i have to check on the server. although im just fooling around with an idea.

you can do it through that I believe