A mouth morpheme adds the meaning to the sign. 
Each clip has the same sign “smart" but each mouth morpheme adds the meaning to the sign. Here is the list in order on a scale from basic to extra:

1. Smart
2. Pretty Smart
3. Acute
4. Gifted
5. Bright
6. Crafty 
7. Clever
8. Intelligent 
9. Brilliant
10. Sharp 
11. Genius 

Thanks to Byron Bridges for his work on a scale of mouth morphemes.