Well, Mr. Mason,
IF the flapping object is indeed in the doorway
And (let us remind ourselves) this conclusion is troublingly hard to avoid.............................
1. This man-------------

-------------- appears NOT to be holding anything that could be the object we see flapping in Towner. Look at what's (not) there when he extends his right arm after the limousine:

2. The woman behind him DOES appear to be holding something that is flapping in the wind, but it is clearly TOO FAR EAST to be the object we see flapping in Towner in the synced frames:

And! There appears to be nothing else in the real prospect between the man in the street and the doorway that could possibly be the flapping object.
Result: The flapping object does indeed appear to be in the doorway.
Given who Coca-Cola Man is (Mr. Oswald), this circumstance suggests large implications for what is really going on.
Bear in mind! Pres. Kennedy (if he is indeed looking at the flag in the doorway) can hardly be SEEING DETAIL on it. No, he can be doing no more than noting the
fact that it is waving.............

He has already seen lots of flags and signs along the parade route. Is there something about
this flag that makes it of special interest to him?
A truly ghastly thought occurs, one that sends us back to the Rothermel memo................