Cybil Shepherd glow… 🙂 another way to achieve it
basic color correct your video,
then
double up your video, from V1 to V2
on V2, put a desaturate filter and a gaussian blur at 8 to 25%.
now lower the opacity of V2, 30% would be a good start, then go up until you are happy with the result.
you can also change the amount of blur on V2, the amount of desaturation and how open the hilights CC 3 way on V2 are. all these will change the look of your glow
about matching sky from cloudy to sunny. this is never simple. the sun affects every single shadow in your shot in a way that only the sun (or BIG expensive lighting) can. when its cloudy, not just color and temp change, but the entire shadow scheme of the shot, and while the first 2 can be fixed, the later is rarely the case.
there are several techniques for sky replacement (look up in google). some involve keying out the sky and colorizing it with color wheels and saturation (secondary color correction). others mask out the sky and replace it with a new one. in other cases its a combination of the two techniques, masks (vignettes) to isolate then key to select.
if shot is moving. you will need tracking.
color can do a pretty good job at all of that.
if you have complex trees on your skyline, the first method would probably work better, as trees can be hard and time consuming to mask.
here are two basic tutorials. none using FCP but you will get the idea.
https://library.creativecow.net/articles/kramer_andrew/sky_replacement.php
https://www.viddler.com/explore/Emeek77/videos/135/
if you are not sure of what you are doing, and can’t bring in someone who can fix it for you.
maybe re-edit to use a minimal amount of bad sky shots? (the viewers never really know what you didn’t use) or maybe exaggerate the difference between the two looks instead of trying to match them.
hope this helps.
Hector Berrebi
Schibber Group
prePost Consulting