Oswald in the doorway: the blog of the Oswald Innocence Campaign, by Ralph Cinque

Here's an interesting frame submitted by the Wizard with his comment.

With regard to the timing of the above image – Bookhout is just bending down/‘being bent down’ during his dive. Bagman is about to see (or is seeing) something fall off Bookhout’s head and is about to rush forward with his bag (or whatever it is) to cover Bookhout's head. He gets there first, while the Nod cop and the white-hatted cop go round the other side to join Harrison in trying to block the camera views.

This photo is just before the Nod 3 gif action: