I could not find any reference to a secondary payload on that Falcon.
I therefore assume that because of its low relative speed, Elvis is a piece of the satellite. For example, there might be equipment on the sattelite that is sensitive to the rocket exhaust, so it is covered while the engines are still firing. Once the engines shut down, they jettison the cover.
Since David Bowie seems to be moving relative to the apparent background (although this is not 100% clear from the video) I would assume that it is a passing object. From the fact that it takes a while to pass the spacecraft, I would guess that it is a larger satellite passing in considerable distance.
As you can see in the screenshot below, the sky south east of Madagascar was quite crowded at that time. My money would be on Iridium 11 being David Bowie, because it has a large radio dish.
Jason 3 is not pictured, but the position on the map would be almost precisely where Saudisat (1C) is pictured. However, Saudisat passed far underneath Jason, so if it was in the frame, the earth would also be in the frame.
Looking through the instruments of Jason-3, Elvis may be a cover for the Carmen-3 experiment. It fits the general shape, and since it is a sensitive electromagnetic device, it may need protection while crossing the inner Van-Allen-Belt. https://jason-3.cnes.fr/en/JASON3/carmen3.htm