Thumbnail covers blog text

I am running WordPress 4.1. I have used the shortcode below to embed a video in my blog post.

[video_lightbox_youtube video_id=lKMHM1My6Zg width=640 height=480 auto_thumb="1"]

Thus, the thumbnail appeared covered the text of the blog post itself. Is there any solution to this issue? I have hyperlinked the URL of the affected post above.

https://www.ads-software.com/plugins/wp-video-lightbox/