Namaste ji, Joammaji.
You've got most of the head bobbles right. The sideways bobble is agreement to something you said. It means yes, when you ask a question in which the positive response is yes. When the positive response is no, it means no.
We also have the nod, and the sideways movement. The nod is yes, and the sideways head movement (right to left twice, or thrice) is no.
If someone is nodding at you and not speaking, they are probably shy or in some awe of you, or they don't want to talk to you and want to run away.
The cheeky head bobble is definitely a sign of cheekiness :) You don't wanna be around this guy! Sab Samajhte!
:D Thanks for making these bright videos, I've been watching them since yesterday.