Not sure what this means:
Mr. BALL. Did you go out of the building shortly after you came downstairs?
Mr. WILLIAMS. They wouldn't let anybody out of the building.
Mr. BALL. How long after you came down from the first floor were you taken over to the Police Department?
Mr. WILLIAMS. I couldn't give you the exact time, but it wasn't long.
Mr. BALL. You can't give me any estimate in minutes?
Mr. WILLIAMS. No, sir; I would not want to say
We see Williams outside the building 8 to 15 minutes after shots (according to Groden HSCA)
How does this fit in with his testimony?
It means Williams was incorrect.....here is Jarman's version. Was he mistaken about who he ran outside with?
Mr. JARMAN - No, sir. I ran, then we ran to the front door.
Mr. BALL - You ran to the front door?
Mr. JARMAN - Yes, sir; and out on the street.
Mr. BALL - You and who?
Mr. JARMAN - Harold Norman.
Mr. BALL - You and Harold went out there?
Mr. JARMAN - Yes, sir.
Mr. BALL - Did you ever see a fellow named Brennan?
Mr. JARMAN - Yes, sir.
Mr. BALL - Where did you see him first?
Mr. JARMAN - He was talking to a police officer.
Mr. BALL - How was he dressed?
Mr. JARMAN - He was dressed in construction clothes.
Mr. BALL - Anything else, any other way to describe him?
Mr. JARMAN - Well, he had on a silverlike helmet.
Mr. BALL - Hard-hat?
Mr. JARMAN - Yes, sir.
Mr. BALL - Did you stay out there very long?
Mr. JARMAN - Just a few minutes.
Mr. BALL - Then where did you go?
Mr. JARMAN - We heard him talking to this officer about that he had heard these shots and he had seen the barrel of the gun sticking out the window, and he said that the shots came from inside the building, and I told the officer that I believed that they came from inside the building also,
and then he rushed us back inside. Mr. BALL - The officer did?
Mr. JARMAN - Yes, sir.
Mr. BALL. From the time that you went down on the first floor until you left the building to go home did you leave the building at all?
Mr. NORMAN. No; I didn't.
I believe in the movie from which the stills you posted were extracted that you can see Jarman being ushered inside. Simplest answer is that Jarman and Williams left via the front door and were ushered back inside after a short period that involved Brennan.