I have over 220 hours on my Varg, and the chain has never come off, I also have not felt the need to adjust it.
That being said, a Buddy had his chain come off once crossing a very muddy area, but he thinks it was caused by a stick getting tangled up in it.
After my first ride, I found the chain slack was out of specifations. I find it difficult to get the chain slack just right so I built a slack gauge that works well. I posted it in another thread here. I only do motocross with my Varg and never had a problem. After adjusting with my gauge, I don't get any chain slap.
I can't watch these makes my blood boil, 100% set up you can only ask these questions and stark want to edit it before it goes out.
Should let me ask the questions no holds barred.