Do you want to embed a video from YouTube.com to share it with your visitors through your BlogSpot blogs, it is pretty easy to do that.
1- Choose your favorite video from YouTube.com.
2- At the left, you will see a code which titled by "Embedded".
3- Copy the code and add it to your post through the HTML window "Not compose window".
4- Add your comment on that video and publish the post.
That is all, happy blogging