Place the video clip on track1. Try this: Place the same video clip on track 2 offset by 1 frame to the right. Set the opacity to 50% Disable the audio on track 2. Any still background will be sharp. Any movement in the video will be blurred by 1 frame which is what you want.
Optodata posted a NewBlue plugin that works in PD365 earlier. It works but you have to buy it if you want to keep it after a trial period.