Saw this on the Instagrams and had to chime in.
When doing accessory work think about why and what you are doing.
Obviously this is to build your bench, right?
If you watch the video, as you lower the weight you are putting it all on your TRAPS.
The decline will make it a little harder to put it in your lats, but you need to focus on lowering the weight the same way as you would a barbell for the bench press.
Try to pull/row the bells down into your lats as you would on the bench.
Keep it off of the traps.
Easy to say, a little harder to do, but do your best.