I have some friendly advice. Please take it in the spirit it's given. I upvoted your post.

I recently posted a how to insert a YouTube to Steemit. The way that you posted your video, when viewing on a mobile phone, about half of the video thumbnail is not visible. It cuts off a bit of the start button also.

Check it out.

https://steemit.com/education/@michaelstobiersk/2-ways-to-add-a-youtube-video-to-a-steemit-post-by-michael-stobierski
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I hope that you find this useful.