It looks like you only uploaded a screenshot/posterfile.
Pls verify: Photo Albums -> Settings -> Basic settings -> General -> Item 1 Enable Video is checked.
Go to the Album admin page and type 20 in the green bar – assuming item 20 is the one – then click Edit
You should see something like this:

If not, delete the item, go to the album table, edit the trashed photos that can be rescued, edit them and delete him permanently.
Now upload the video (.mp4 ?) to the album where it should be.
If the file is too big or it takes too long, ftp the file to your depot (see the import page where it is) and import him to the right album
You will need no posterfile
Jacob,
Thank you for the prompt reply. This slide is configured with an external video link vs. uploading the video to the site. I confirmed the setting you suggested is checked, but do not understand how to “go to the album table, edit the trashed photos that can be rescued, edit them and delete him permanently”.
I deleted the slide and re-added it, assigning the external link but hovering over the image does not indicate there is a video that can be viewed.
Appreciate your additional thoughts on how to proceed. This site is one of many in a multi-site setup. I’ve not had this issue with the other sites where I’ve switched to using external YouTube video links.
Try Basic settings -> Links -> II: Links from standard images. Tick the box under PSO on item nr 6 Slideshow
That’s it, thank you Jacob!!