I have Virtual Directory set up successfully. It serves most common file types, but not .mkv. I've tried adding new Handler Mappings via IIS Manager, but to no avail. I'm choosing the "Add Managed Handler" and reading has pointed me to try things such as "video/mkv" (also application/octet-stream) in the "Type" textbox, but I just get an http error saying:
Could not load type 'video/mkv'.
I note the drop-down appears to be libraries (e.g. System.Web.DefaultHttpHandler).
How do I set up these handler mappings?