Go to #52 and then at 29 seconds in there is the briefest of views of two furtive looking men in black hurriedly moving from left to right. Thanks to a Kelly researcher who knows the geography I can say that this shot was taken looking south east with Harrowdown Hill in the background. When looking at Google Earth it can be seen that there is a particularly large field immediately to the north west of Harrowdown Hill and extending to a track leading from the village of Longworth to the unoccupied Thameside Farm. This field appears to be an amalgamation of two with a length of hedge removed to make it a single unit.
The section of hedge taken out is about 220 yards long. If it was extant in July 2003 and the two men were walking down the eastern side of it then the cameramen wouldn't have seen them. They will probably have thought that it was bad luck to be caught by an inquisitive lens. As with the more familar track that goes up to Harrowdown Hill the drive up to Thameside Farm runs approximately north - south and is less than half a mile west of the Harrowdown Hill track. The latter of course was quickly closed off to the media and so it's "well done" to the TV crew to have spotted this alternative route to get at least reasonably close to the Hill.
Going north beyond Thameside Farm itself there are disused farm buildings closer to the river and from the direction of travel it seems possible that the two men in black might have come from this area. The three men in black seen at about 10.30 weren't too far from this spot either.
Were the two men in black two thirds of the three men in black, or perhaps one of the two men in black was one third of the three. I don't know but I would have thought that at a minimum the two groups had some sort of common function that day.
According to the walker the three men heading towards the river path were empty handed but this evidently wasn't the case with the two chaps caught on film. The coat of the leading man is hiding what he was carrying.
I really don't know about all of this, one problem we have is not knowing when the cameraman went up the Thameside drive. But the description of the three and the video evidence of the two does suggest to me movement with a good deal of urgency about it.