Responsive Video
Most video players aren't suitable for responsive web pages. The MP4 video file needs to be inserted in two sizes and have a lazy loading function to prevent it from slowing the page load and time to be interactive (TTI) which should be less than 2 seconds.
SEO
A video needs a description for the visitors and the search engines - just like an image. Using a lightbox launched from an article provides more info and reduces the onload content.
Hosting
Using self hosted MP4 is way better than using hosted video like Vimeo, Wistia or YouTube. If hosted video is used it must be launched in a lightbox and have a lazy loading function to give reasonable performance on mobile devices.