Hi  I am just in the process of trying to increase the media file size: 

I have updated my web.config  and added

  <location path="umbraco" allowOverride="true">
    <system.web>
      <uploadRuntime useHttpModule="true" />
      <httpRuntime executionTimeout="99999" maxRequestLength="40000000" />
    </system.web>
  </location>

and 

  <security>
      <requestFiltering>
            <requestLimits maxAllowedContentLength="40000000" />
      </requestFiltering>
 </security>

this is suggested ina  couple of posts, however I am getting the following:

which would indicate accordign to the microsft IIS update that it was hitting the max fize of the IIS (default is 30, but I have pushed that also), see the setting above

I've also double checked my permissions,

 I've made sure the network service is good etc.

any thoughts as to why and how to fix this would be super useful

Ravi