All the films Criterion distributes, including out of print titles, stuff in Eclipse sets, and their stuff on Hulu Plus. Also includes whatever video bonus features on all that DVDs that were listed on Letterboxd, including documentaries/making-ofs and the like.
And now the stuff on FilmStruck, which is unfairly only available in the US.
2020 update just criterion collection stuff, not their new streaming service. spine numbers only applicable until the first numbered collection