Database of Recorded American Music or DRAM, is an audio streaming service with complete liner notes and essays. Focus is on American composers and features the following labels: New World Composers' Recordings (CRI; complete catalog), Albany Records, Cedille records, Deep Listening, Frog Peak Music, Mode Records, and others.
Classical Music Library includes all major genres from medieval to contemporary periods. Currently the site has over 75,000 albums with more than 1.2 million tracks.
ProQuest, the parent company of Classical Music Library, has created a Classical Music Library Guide that describes the database and gives tips on searching and how to create playlists.
You can also find opera performances and documentaries in streaming resources that are not limited to music or opera. Some of the below databases only have a handful of titles, but you might find just what you're looking for!
Films on Demand If you are working with younger children, check out their "Opera Easy" series.
Naxos Music Library offers streaming access to more than 141,480 CDs with more than 2,190,800 tracks of both standard and rare repertoire. Over 800 new CDs are added to the library every month.
Naxos Music Library has over 700 opera libretti and synopses.