Excellent question! This caused me to dig rather deep and still haven't found anything totally satisfactory. The issue is that the Jupiter-C is a bit of a special duck. Primarily used for warhead nose cone re-entry profiling, it was known back in the late 50's that this rocket COULD put a satellite in orbit through use of a fourth stage but no program was in place at the time to pursue it. Perhaps Cold War ethos wanted to keep this capability under wraps for as long as possible. Even MORE interesting is that the Jupiter-C program was mothballed and the 3 rockets of this variant were purposefully mothballed pretty much by one general acting on his own initiative rather than being dismantled as originally planned, in order to keep them available.

All that being said, the issue here is with what is called the "AFT" section of the rocket. This is the skirt that sits atop the Redstone rocket propulsion unit (all part of the first stage). So far I have been able to uncover a decent schematic for this section only for the operational Redstone ballistic missile. As such this appears very differently from the one used in the Jupiter-C configuration:

See page 31 of this document:

http://www.myarmyredstonedays.com/pd...dstone_001.pdf

Here it looks like the jet vanes and air nozzle assemblies were removed for the Jupiter-C configuration, however the 4 counterforts remain. Also in the -C configuration the instrumentation section is more conically shaped and supports the rotating "tub" assembly used in stages 2, 3 and 4, absent in the operational missile configuration.

Here are a couple of pictures here that better show the -C AFT variant he

http://upload.wikimedia.org/wikipedi...Explorer_1.jpg

http://www.enterprisemission.com/Jupiter-C_Gantry.jpg

Note: I don't endorse the content of the 2nd link but it does have a good photo of the upper end of the Jupiter-C that can withstand significant enlargement.

So there are two possibilities here. Note the first picture shows light emitting from the AFT section in two places. First as white light being emitted from the wide end (bottom) of each of the counterforts and an additional red light being emitted at two points nearly 180 degrees apart. Normally I'd go with the white light from one of the counterforts, but for the video you provide, it looks to be in the wrong place and only one light source is visible in the film. So I am at a loss.

There is one other remote possibility but I think that highly unlikely. Page 81 of the first cited document talks about the positioning of a porro prism used in conjunction with a "laying kit" to "orient the missile to allow the lateral guidance system to be keyed to the theoretical ballistic path from launcher to target". Perhaps this object was replaced in the -C AFT skirt with something that also emits light! It is in about the correct position.