I don't think it's anything bouncing. I think it's people playing catch with a larger ball, standing somewhere over the ridge so they are hidden from view.
The sphere seems about the right size and appearance of the popular French obsession of Petanque or Boules where outrageously accented enthusiasts hurl reflective steel balls high and far in the air trying to land near the jack and other shiny balls. There is a version known as extreme petanque where people take the game to difficult or exotic locations. Source: https://www.youtube.com/watch?v=z4b9rp5YJ_c
Maybe something like this? A spherical drone, (the above is a "Harry Potter Golden Snitch" drone once sold by Urban Outfitters). Possibly flown by a person over the ridge of the hill? I don't see "wings" or propellers on yours, but is it possible they may have been moving fast enough to blur into the background? Very interesting, no matter what it was; it reminds me of the mystery of the Solway Space Man, (pic below)