This is because you are requesting a url like: "/Content/Details/1"
so that relative path will point at: "/Content/Details/1/images/butterfly"
. You don't have that folder on your server, so therefore it will not be found. Instead you can resolve the url server side so that it will find the correct folder. Just change "images/butterfly"
to <%=ResolveUrl("~/images/butterfly.swf")%>
and move the folder out of your views folder as files can not be requested in the views folder by default. If you really want to have it in the views folder you will have to change the web.config
in the views folder to allow that.
Remember that relative paths like yours will be resolved client side. This is nothing special to asp.net mvc. The client doesn't know what serverside framework you are using. The client just looks at the url and resolve it from there.