One claim is that the gun can fire when dropped at a certain angle from a certain height. The voluntary "recall" lets you send it back to Sig and they replace some parts. I think the cause was because the trigger itself was bulky enough for a drop to give it enough inertia to fire, but I'm not 100% sure on that.
The other claim is that the P320 can fire without being dropped, and while holstered, seemingly on it's own. That's all I really know about it.
I own a P320, and I consider it an unsafe weapon at this point. I have not had the self-recall fix done and I'll never chamber a round in it again, so I guess it's a paperweight now.
The only time my gun has went off was when I pulled the trigger. Has your gun ever went off without pulling the trigger?
Most of the videos I see on YouTube are people who were fiddling with the gun, in some kind of physical altercation, or carry some sort of back on the side they carry. I didn't get the fix from Sig either.
All that being said, I'm not trying to say there is definitely an issue with the P320, but there is enough out there to give me some doubt. Perhaps there will be a fix at some point, but until then it's just not worth it to me.
This also isn't happening with other guns. If you google any other gun brand and the words unintentional discharge, you will still only get results for the P320.