1 Open Settings->Options->Sources tab, select YouTube.

We have here different video embedding types:

- Object/Embed. Not all browsers support this type. It used to use for old browsers before html5 support.

- iFrame. It should work for the most browsers.

- iFrame for new browsers. If you use up-to-date Firefox, Chrome, Safari browsers you can set this type.

- Watch url. This is preferable type for WordPress based blogs.

If you cant see video in your blog you need to try different video embedding types - specific for your blog platform and browser you're using.

2 If you don't use custom Drag&Drop template you can restore it to default. Just click Restore to Default button and then OK. It will reset your template to default one - with correct parameters.

3 Perform some search for YouTube, add one result to PostBuilder. Open source view.

Depending on video embedding type you should see here video object with correct parameters.  Please find "height", "width", "src"  parameter for object/iframe embedding type, and youtube watch url for "watch url" embedding type. If you cant find one of the parameter, or it's empty you need to reset your YouTube template to default value.

4 Try to publish.

If you cant see video in your post - click edit and check HTML source code. You should see parameters from 3. Otherwise try to reset Youtube template/video embedding type.