I know that video thumbnails are sometimes really pain in ***, but you got some video thumbs with video names that won't tell what it's all about or what is the game in question.
Also if you are like me, that prefer more "offline" approach of doing voice overs for game videos, then it's better to record your game play first and then taking the parts you need and then do voice overs to them.
I personally, in my opinion get little better to talk "online" and do more straight to video commentary by doing livestreaming in alternative channel or another platform.
I personally use Adobe's Sparkle to do YouTube thumbnails and other social media thumbs as well.