Substitute the word “placed” for the word “hide” and Oswald therefore placed his bag someplace in the loading dock area just before he entered the TSBD back door before BW Frazier follows some 30 seconds later .
BWF does state seeing Oswald carry a bag INTO the back door. However the door that BW Frazier referring , is actually the back door of the attached roofed annex bldg , which is the enclosed part of the loading dock, and thus NOT the back door of the TSBD bldg., which is the 2nd door AFTER entering the loading dock annex bldg back door.