For future ref, you can duplicate the footage, pull out the color, use levels to crush down the image so it’s mostly black except for the white areas. Then blur this and use the ADD transfer mode back on top of the original layer.
If you want to simulate the starglow effect, instead of a regular gauss blur, do a directional blur to get a horizontal streak, then duplicate this and change the blur to vertical, then ADD/SCREEN transfer mode the whole lot back on top of the original footage. Then you’ll get your star shape. Also try tinting these top layers for the colored effect.
Chris Smith
https://www.sugarfilmproduction.com