Which frames matter most

Both systems must decide which frames matter most. Sampling every 45th frame treats all moments as equally important, which they are not.

The mechanism that can learn that weighting is attention. Deep dive 17, opened live right after section 06, splits it into heads with the reshape and transpose of section 04. Appendix B builds it from two einsum contractions and shows that its mask — setting padded positions to -np.inf before the softmax — is exactly the variable-length solution from Part II.

So the group exercise’s last question is answered later the same morning, by an operation you have not met yet.