Green Screen Overlays
Free Assets for Filmmakers / Green Screens / Overlays / Stock Footage / Motion Effects Elements
https://www.pinterest.com/pedrosilvamalin/free-assets-for-filmmakers-green-screens-overlays-/?lp=true
After Effects
Free After Effects Templates - RocketStock
https://www.rocketstock.com/free-after-effects-templates/
Soundtracks
General
r/Filmmakers - Free Assets for Filmmakers | Film Riot
https://www.reddit.com/r/Filmmakers/comments/7b9bjo/free_assets_for_filmmakers_film_riot/- https://www.shutterstock.com/blog/over-120-free-video-assets
Free Video Assets Archives - The Beat: A Blog by PremiumBeat
https://www.premiumbeat.com/blog/category/free-for-video/