Google Docs Shortcode doesn't support older presentations
As per an email convo I had with Chris, Chris noted on CAC that older Google Doc presentations do not embed.
Should be quite easy to support the older format.
Also, Chris noted that Google has slightly changed the interface for configuring the docs. If you login to Google Docs, create a new doc and then click on "_File > Publish for the Web_". You'll notice that there is no longer a checkbox to automatically update.
Scott: The first screenshot in the codex article needs to be updated.
#1 Updated by Raymond Hoh about 9 years ago
In commit 37d694e, I've added an update that should allow older presentations to be embedded.
So you should be able to use the older presentation URL format and it should display in your post.
Update: the code is up on cdev so feel free to test and let me know if there are any issues!