The @TeamYouTube auto-gen thumbnail experiment doesn't sound bad with .03% of viewers affected but that's about 30K of my subs. So at 16 uploads a month I may have half-a-million potential views compromised because I look like I'm midway through a sneeze in my thumbnails. Great
To be honest your current picture for twitter could be mistaken for halfway through a sneeze so perhaps their algorithms are better than we think?