Squint test
Blur the feed the way it looks at a glance. If your thumbnail still reads, it will stop the scroll.
Will they click?
Drop a thumbnail, write a title and see your video next to everything else in the feed — on a phone, on a laptop and in the sidebar. Compare two versions before you post.
How the title reads
Badge zone
The length badge sits on the bottom-right corner. Keep faces and words out of it.
A next to B
Put both versions in the same feed. The one your eye lands on first is usually the one to post.