In Nov 1964 no less than 12 C-135 were allocated to the Apollo Support Program. These huge planes can dive to simulate weightlessness and can easily acommodate a mock-up CSM. The weightlessness lasts only a few minutes so any filming has to be timed just right. Collins' non-floating jacket indicates that some gravity was present and this timing was off.
Yesterday on YouTube nasascam posted a vid "Anything NASA Can Do, The CIA Can Do Better". See this and his video response and read info.
Unfortunately for America there are oath-breaking traitors in the NASA/CIA/ Pentagon who have, and still are, committing crimes against the American people. The despicable Apollo fraud is just one of these crimes.