We just added a new feature requested by one of paid account user. In the past, you can only embed presentation which is open for public in your blog. Now, we expand the embed possibility to password protected presentation, too. Here is an example (password: vcasmo):
Note: only presentation owner can get the embed code for password protect in the presentation watching page. Moreover, the embed code is slightly different from normal embed code. So, please go to your presentation watching page directly and get the correct embed code.