Blogger makes it easy to embed a youtube video into a blog post. Typically the post will display the youtube video player with the selected video. However, on some phones the video player might not be displayed. The problem may be in the class attribute of the iframe tag being assigned "BLOG_video_class".
To check for this issue, open the post for editing. Ensure the view is set to HTML View. Look at the class attribute of the iframe tag. If it is assigned the text "BLOG_video_class", delete that text (leave it as class="") or delete the class tag and text and quotes altogether.