Android not playing HTML5 video on HTTPS

Question

I am using HTML5 element to play a sample.mp4. It plays fine if using HTTP protocol. If I change the URL to use HTTPS, it will give error "Sorry, this video cannot be played." The SSL certificate is valid. I have tried on both IIS and Apache server.

<video src="sample.mp4" id="myvideo" />
<a href="javascript:void(0)" onclick="document.getElementById('myvideo').play();">Play</a>