HTML5 Video to play when button clicked

On my site I have a small video playing in a loop in the top left corner, I want to click on a button and replace the video with another, then when the video has played I want to go back to the first video. There will be 7 buttons to click playing 7 videos, one at a time of cause.

I’m not that savvy with Javascript to do this, I would appreciate any help on how to do this with HTML5 video.