Internet is full of videos, and you have a power packed set of tools for IIS to make media streaming top-notch experience. You have IIS Media Pack enabling intelligent progressive downloads, smooth streaming, throttling, etc. You have tools from Microsoft such as Expression Encoder which helps building rich videos. Expression Encoder also gives you an option to upload the videos from the tool itself directly to the web server.
I was working with one of my customer who was trying to upload a large file to the web server from his Expression Encoder, and failing with 404. While checking the IIS logs, found that it was really a 404.13 which says the content length is too large.
You should follow this KB to increase the maxAllowedContentLength to be able to satisfy the size of the file you are trying to upload. By default, it is just 28.6 MB. So, if you are uploading any file greater than 28.6 MB, it will fail.
This applies for any file you might try to upload, for example using the ASP.NET File Upload control. Thought I would just make this quick post for those who use Videos heavily, and upload them from the Video Editing tool (such as Expression Encoder) to the web server directly.