The problem may be how you are adding the code and when you are adding it. YouTube videos and Google Docs need to be added as a final step for writing your post.
To add you need to click on HTML Tab, add the embed code and them immediately click Publish post. Do not click back to Visual Tab before publishing the post because it may delete the code. Then immediate close the post. If you need to edit that post you may need to add new embed code.
When ever I embed things such as youtube videos or googledocs they will be there in the edit mode but not appear when I publish the post. The work is my own. Why is this and what do I need to do?