HTML5 - mp4 video does not play in IE9

Question

I have an mp4 video that I want to play in IE9 using HTML5 tag. I added the MIME type to IIS 7 so if I browse http://localhost/video.mp4

Answer 1

I have a base profile .mp4 video which plays on one server, and does not on another.

The only difference is:
one gives a header "Content-Length: ..."
the other "Trasfer-Encoding: chunked".

I found out that Content-Length is not needed, it is only important, that there should be NO chunked header. This can be done by turning off compression (deflate or gzip) for .mp4 files. How this can be done is another issue and another topic: How to disable Apache gzip compression for some media files in .htaccess file?

There can be another server issue:
it has to give "Content-Type: video/mp4"
and NOT "Content-Type: text/plain"