You might think you’ve hit on a gold mine when you stumble on to the surfeit of theater lurking in YouTube. Know nothing about Eugene O’Neill’s “The Iceman Cometh”? You can spend what will seem like a fortnight with John Frankenheimer’s 1973 film version. Curious to see Jason Robards’ take on Grandpa Vanderhof in “You Can’t Take It With You”? It’s there. Jack Lemmon and the young Kevin Spacey show up in “Long Day’s Journey Into Night.”

But caveat emptor when browsing the free rummage table that is YouTube or Vimeo. That tag that suggests you’ll see “West Side Story” is true in name only. “Dracula, the Musical” has the shaky hand and unsteady focus of a bootleg. “A Chorus Line” is perhaps the most astonishing example of bait and switch — an “original cast” production that appears to date to 1913.

If your goal, though, is research, the Internet’s trash can be a treasure. An actor might want to look at a clip of Laurence Olivier’s “King Lear” and compare it with Ian McKellen’s take. Choreographers might pull a move from a dance line.

Michael Gruber, who is directing “Fiddler on the Roof” at Artistry at the Bloomington Center for the Arts this spring, wanted to study Russian folk dance. It was just a few clicks away.

Sara Bahr, an MFA student at the University of Minnesota, uses the social site Pinterest to share images with directors and designers. “It’s like giving the director a photo album with 20 or so options,” she said. “Then we can talk on the phone while we’re looking at the Pinterest boards.”

Dance Prof. Joanie Shapiro uses Vimeo to post rehearsal sessions. Much like filmmakers viewing daily “rushes” during production, “you get an accurate look at what you’ve done that day,” she said.

Director Peter Rothstein also makes short videos of his Theater Latté Da productions. “We do two videos with rehearsal and interviews, then we post a third after opening, with video from the show and bites of reviews,” he said. “We’re hoping to get people to invest in the work of the company.”

But he shies away from too much research in developing shows, not wanting “to tarnish my imagination.”