CodePlex requires two request-verification-tokens to retrieve the redirect-URL to download the actual file (dated 2013).
One token can be retrieved from the applicable HTML-page. The other token can be retrieved from a cookie.
However, AFAIK Ketarin does not support reading cookies.
In order to be able to use Ketarin to download from CodePlex I hereby request the feature to read cookies.
Preferable in such a way that it is possible to store the data in a variable (e.g. "Content from Cookie").
Customer support service by UserEcho