IE10 not playing a video when using the <video> tag, but plays it when requesting the video directly

Question

I have a webpage with a tag on it with the following markup:

Answer 1

When you paste the URL to your browser it doesn't use HTML5 player anymore, so it doesn't say that it is really a supported file; only that the file path should be valid.

According to wikipedia, IE10 supports (not only) H.264 for video and AAC for audio - these are very common formats for mp4 container. Chrome's support is much wider (video- and audio-wise).

The problem is that the Intro.mp4 file might have different formats altogether (the file could by just renamed or created using unsupported formats).

I'd look into the file using properties->details or third party programs (for example Media Info).

I don't think it is IE10's issue. The only similar one I've found is when the user was too specific using unsupported format of used codecs ([...] type='video/mp4; codecs="H.264, AAC"' [...]).