No. Rifled Slugs do not spin stabilize. They might rotate a bit due to drag, but it's not stabilized by spin...
Who even asked this question?
5 points from Griffindor.
Well the video under discussion argued, with some simple visuals, that a "rifled slug" picks up sufficient spin during barrel passage to assist in stabilization. The unrifled foster type slug used for comparison was of an apparently different fore and aft weight distribution.
Any cogent discussion of the evidence presented ran full steam into a massive iceberg with resultant Titanic thread drift into bullet resistant vest penetration.
No assistance from the fictional Griffindor