..... I think it is actually the crowd and other effects that are added into the composite to make it look like an enthusiastic crowd. .... Believe it or not it is quite easy to do ... and is done quite often.
.... My hypothesis is that the network had to use the footage that the reporters filmed earlier on, which was probably not very flattering to her image and campaign ..... So .... Enter the SPFX crew that the network (And all networks) has on their payroll .... they overlapped the crowd in the foreground and rotoscoped Hillary's background out and replaced it with a still flag images of the stage. The SPFX Dept was probably rushed and missed a few details which are shown in this video. In the business this is called "Fixing it in Post" .... or in Post Production.
..... Anyways ... That is my two cents worth!!
that could very well be true. It looks odd and slipshod. Humans are very adept at spotting fakes, and this just doesn’t look right. Kind of like when Al Gore’s handlers told him to act like an Alpha Male. Just creeped everyone out.