Yep, tried the deactivate all plugins except WPSP route, but thanks to the screencast of your post, I found out what is “going on” and I am not sure if it’s a WPSP or a WP thing.
This is what I have on that page for the gallery, which shows the shortcode in the excerpt:
[gallery link="file" columns="2" size="full" ids="199,198,197,196,195,194,193,192,191,190,189,188,187"]
When I get rid of the options, and just have this, it “works”, that is, the shortcode is not displayed in the excerpt:
[gallery ids="199,198,197,196,195,194,193,192,191,190,189,188,187"]
Hmmm … 🙂 But I would like to use the options 🙂