Thanks for the answer, Michael,
but the problem is, I’ll be having hundreds of user-uploaded pictures (which will be named 001.jpg, 002.jpg etc and sorted in separate folders for each user automatically) and I’ll be needing some sort of script, which will tell AE to replace placeholders with those images and run render for all those separate folders.
For example, I’ll have 10 folders named 001, 002, 003 etc with 5 jpg-s in each, named 001.jpg, 002.jpg, 003.jpg etc., and I’ll need 10 video outputs with those different packs of pictures.