I am sure this plugin will become very popular quickly.
I just tested it with latest multisite install and it works out of a box, but has two bugs:
1. it uploads just full size image
2. it overrides files with same name
Instal is not fresh but I'll test that also and post a result when finish.
Also, I looked at code and notice just 3 image extensions, does it means that it is not possible to uploads any other file type.
Would be great if bugs could be fixed and to having a feature to allow uploading any file type and size that s3 allows so to take advantage of uploading directly without touching server.
Anyway thanks for a great plugin.