Hoping to get this figured out, perhaps by someone more familiar with the plugin than I am… I have been digging for 2 solid days now and several other days in the past, still with no success. I have stumbled across 2 articles on placing the slideshow sidebar widget in the header:
https://www.scotproof.com/inserting-a-nextgen-slideshow-in-your-header/
https://www.mackmangroup.co.uk/adding-a-nextgen-slideshow-to-your-wordpress-template
Neither of those solves my problem, but I thought they might help someone else figure this out. I continue to believe that if the slideshow can display random images from ALL galleries in the sidebar widget then it can do it in a post.
I will add that there is a “hack” way to do this by turning on the sidebar widget, load your site and copy/paste the source code into a post. What you should end up with is something that looks similar to this (depending on your settings):
[Code moderated as per the Forum Rules. Please use the pastebin]
Obviously yours will look different based on the options you have defined for your slideshow, but I was able to make the changes in the widget and have them appear in my post. The problem I ran into was that when I removed the sidebar slideshow widget (I didn’t want the slideshow in my sidebar) it stopped working in my posts also…
As I said, this is a hack way to do this for sure, but it might work well enough for some people, or even help someone figure out the proper solution. Please keep in mind that this is all flash stuff for people using the flash imagerotator.swf file.