Video in a div tag (or figure or whatever). Put a button in that div as well, then position the button over the top of the video (eg position relative on the div, position absolute on the button + the positional CSS - right, top etc).
[Edit, slightly advanced, but I’ve had to implement this umpteen times and I think it’s an issue you might stumble across] ideally you want your videos to be the same size, because (again, ideally) you want them to resize responsively, and it’s easier if you have a single size as they’ll have a consistent aspect ratio. But they aren’t and you do want resizing, you can set the video to absolute position as well, set a with/height on the div and make the video 100% width and height, and use JS to calculate resizing on the window resize event. Here’s the first example I got from Google, makes a bit.more sense if you can see what I mean (images, but works the same with video): https://www.sitepoint.com/maintain-image-aspect-ratios-responsive-web-design/