Insert HTML5 video tag when clicking the button using jQuert

Insert HTML5 video tag when clicking the button using jQuert

I would like to make it like below.

#1 The video file like .mp4 doesn't download when the page is loading.
#2 The download start when clicking the button like "Start Movie"
#3 Auto play using "<video></video> tag" in the page after downloading.

*no downloading video file for users don't want to watch.
*no page transition for usability.

I'm confused how...
Thanks for your help or advice.