Chanen does a Jam at :12. It's an advanced skill that only Memmel (see video above) and Raygoza have competed recently. Many Russian coaches call it an "invert." You need to have extreme shoulder flex, prior shoulder invert skills and eagle grip skills.
Some American coaches refer to a "jam" as an inside stalder. See Nica at :22 http://www.youtube.com/watch?v=4am8HHbgFrk This skill is very common at elite. Kyla Ross also has a lovely one.
Just guesses based on the word "jam."