You should have a look into the web.config
file within the DynamicData folder
<system.web>
<httpHandlers>
<add path="*.aspx" verb="*"
type="System.Web.HttpNotFoundHandler" validate="true" />
</httpHandlers>
</system.web>
any access to an .aspx file will be redirected to a HttpNotFoundHandler!
Within CustomPages folder you may place your own - customized - dyanmic data template pages for any kind of entitySet.
Just create a subFolder with the name of an EntitySet and within this folder, create (or copy) your new templates.
Anyways - this new templated customized pages will be accessible only by your defined route(s) (eg: new DynamicDataRoute("{table}/{action}.aspx")
)