It's the first ever commercial for Smosh stuff (shirts in that case). Entire video is made in stop-motion. Ian (with probably Anthony beat-boxing) creates the background music while Anthony speaks:
Limited Smosh shirts now available!
Guaranteed to raise your sexiness by 60%.
(with quieter voice) Sexiness not guaranteed for ugly.
- Anthony showed off his beat boxing skills on a Lunchtime with Smosh, as well as on his YouTube channel in a video uploaded in 2018, which makes it much more likely that the beat boxer was Anthony.