Here is the same image from the Sixth Floor Museum copy...
The Museum copy does not include the notch, but you can still see a partial image...

I believe the very top Bell still frame is from "The Lost Bullet" (2011). When I get the time I will frame-by-frame my copy of "The Lost Bullet" to see if that same still frame is cropped in the DVD. I'm not big on anything coming outta the Sixth Floor Museum (jfk.org). I do appreciate that opening :40 of the Darnell Film that they released about 1 yr ago. I think the museum "quality control" probably feel asleep at the wheel on that :40 release. There's some very revealing images within that :40.
The specific movements of Zapruder after he got down from the pedestal remain a mystery. Also, how long Zapruder stayed inside the shelter and specifically who was inside it with him. Once again, the Old Guard JFK Assassination Research Community feel on its' arse. Zapruder "no show'd" his scheduled interview with Josiah Thompson for his blockbuster, "Six Seconds In Dallas". This tells you all you need to know. Some of these main players took valuable information with them when they exited the stage.