This is an example of a 3rd party video embed. This video is hosted on YouTube and this website is displaying it using an iframe. Visitors to the site will be able to use the controls on the video just like they would if they were using the YouTube app.
The big video at the top of the page is an example of a .mp4 video file hosted on this website. Large video files can take long to load, so it's important to keep optimization in mind when going this route.