Uploading a .mp4 file and accessing gives a 404

Questions
1

I have no idea what is happening, but this is the situation:

  1. We have a asp.net wizard control that we use in umbraco
  2. The user uploads a .mp4 file to the server via this wizard
  3. The file is correctly uploaded to the server (no validation errors or server side errors etc)
  4. The file is shown in the umbraco media folder
  5. The file is present on the filesystem and can be played via quicktime
  6. But clicking on the link to the file (backend and frontend) will return a 404 error from umbraco
  7. Other files like images and pdf files work as espected (you can access and download them)

Does anyone have an idea what is causing this or how to solve it?

We are using Umbraco v 4.7.0 (Assembly version: 1.0.4163.19946).

This is a companion discussion topic for the original entry at https://our.umbraco.com/forum/28919-uploading-a-mp4-file-and-accessing-gives-a-404