html5 video thumbnail

I switched to self-hosted html5 videos in order for pages to load faster. But I’m disappointed with the fact that I can’t assign an image (thumbnail) for a self-hosted video media element. I know, I can use native wordpress shortcode, but I don’t like the appearence of that player.

So, is there a way to assign an image thumbnail for a self-hosted video?

I have installed Video Embed & Thumbnail Generator https://wordpress.org/plugins/video-embed-thumbnail-generator/, it has a nice video.js player and lets assign thumbnails, but I’d prefer to stick to the theme’s player and keep the number of plugins close to minimum.