Interesting, I'm curious about the impact on wildlife and the way they switch the full nets for empty ones.
They imply there's an overflow system in place I'd love to know how that works
At least one of the pictures shows the nets are on pipes that drain an open cistern. It appears that if the nets get clogged, water will fill the cistern and flow over, bypassing the nets. Seems like a fairly reasonable fallback solution until the nets can be cleared and put back into action. Other pictures show netted pipes that don't appear to have such a cistern, so I do wonder how overflow is handled in those cases - maybe a cistern upstream that's not visible?
More info on the company manufacturing those http://stormwatersystems.com/trash-traps/ They also make trash collecting bots boats.