Some servers don’t have an associated MIME type to support MP4 files. As such, they fail to play MP4 files. To correct this, you’ll need to configure the MP4 MIME type in IIS. This tutorial walks you ...

Google's results are giving me conflicting answers. Some pages say "video/msvideo", and some say "video/x-ms-wmv". I'm thinking the second one is correct because the first one is for .avi ...

Are the PDFs saved as "optimized for fast web view"? That should allow Adobe Reader to start displaying the PDF as soon as the first page is downloaded.