Oh, one other quick white balance/color matching hack if you don’t have a Macbeth chart or gray card handy. Another fine use of “Difference” blending mode lol. Example he does is in Pshop, but translates 1:1 in AE. Works pretty well for the most part. Otherwise, get Red Giant’s VFX suite, dump it all into Supercomp, and away you go lol.
Video:
Lastly, In regards to compositing your shadow catcher AOV, one way that seems to work pretty well is to duplicate the background footage, set it to multiply and pretty much use the AOV as either a luma matte, or you can use the Set Matte effect (in channel effects I believe). I’m pretty sure the way to composite shadow aov’s in general is to ADD it to the diffuse lighting pass if you’re compositing your render layers to create a beauty pass, so in principle it sort of works in the same way. I may be wrong there, but the results end up feeling a bit more natural and doesn’t demand a ton of adjustment layers to dial it in. Just my 2 cents.