With so many video-chat applications already on the market, it sounds like a silly idea: build a new one while pretending the others never existed.

Yet that was what the cofounders of San Francisco startup Rabbit did in 2011, and it seems to have helped them dream up something original. The result, now in a free private beta as a Mac desktop application, seeks to make video chatting less like a scheduled event and more like an ongoing hangout session. Participants can even watch movies with an unlimited number of friends.

Rabbit emerges at a time when video chat is increasingly popular—especially among younger users—and an ever-growing number of devices capable of streaming video are connected to the Web. A report released last year by the Pew Internet & American Life Project indicated that 37 percent of kids ages 12 to 17 use video-chat applications.

Video-calling services have already multiplied like, well, rabbits: well-known examples include Skype, Apple’s FaceTime, Google+ Hangouts, Tango, and ooVoo. But Rabbit hopes it can stand out from the pack. Its distinctive features include simultaneous video-chat and content streaming and little on-screen bubbles that can hover atop other applications, showing who is participating in the chat.

In some ways, Rabbit’s design harks back to the early days of online chat. For example, before you can start a conversation you need to either create a “room,” which you can then invite others to join, or wait until someone else asks you to join a room. There is one public room, appropriately titled “Hop In!”—but most people I saw hopping in there quickly bounded away.

Once you are inside a room with a few buddies, though, Rabbit’s aims become clearer. Everyone you chat with shows up in a circular frame, and the person currently speaking (or speaking loudest) is perched in a larger circle above the others. The bubble shape is intended to obscure the background and make you forget that everyone is in a different place, cofounder Stephanie Morgan says.

People in rooms can further subdivide into smaller chat groups, each represented by an on-screen bubble showing the current speaker in that group at any given time. Hovering over one of these little groups reveals who’s in it, what interests they share, and who within the group each member is friends with on Facebook. You can listen to the different conversations and flit from one to another.

Like many other video-chat applications, Rabbit allows you to share your computer screen with friends. But whereas some applications cannot share audio, Rabbit makes it possible to share videos, music, and other Web content in real time, whether it’s music playing in Spotify or a TV show streamed from Netflix. You can also share just a portion of your screen, if you’d like.

Morgan explains that while Rabbit captures conversation audio that is fed into your computer when you speak into a microphone and streams that to your friends—as video-chat programs usually do—it also captures video and audio directly from your computer so they can be streamed as well. This means you can have conversations while sharing a TV show on Hulu, although the quality of that content on your friend’s end will depend on how good your computer and Internet connection are.

And if you do have conversations over streaming content, Rabbit will detect this and respond by automatically lowering the volume of the video, bumping it back up when it determines that the conversation has ended.

“The whole idea for all of the design, including the technical design, is to have Rabbit be really responsive and kind of organic, and blend into the background,” Morgan says.

For now, the application is available only on Macs running the latest version of Apple’s operating software. This is partly because Rabbit’s method of capturing audio doesn’t work on existing mobile operating systems or over the Web, Morgan says. Eventually, she hopes to offer Rabbit on other platforms, and on mobile devices, too.

I tried Rabbit and found that it’s still extremely deserving of its “private beta” label—streaming videos tended to look pixelated, and talking over them sounded choppy, despite up-to-date computers and speedy Internet connections. But friends I spoke with did feel a bit more “there” than with, say, Skype, and I enjoyed being schooled on details of Downton Abbey while watching with a friend several cities away.

Even so, it may be tough for Rabbit to get enough users. While video chat is increasingly widespread, even some efforts with big-name backing haven’t taken off (see “Napster’s Founders Try a Video Chat Do-Over”). Lee Rainie, director of the Pew Internet & American Life Project, says this may be because social expectations are much higher when you’re on camera. Some people prefer not to be seen; it’s much harder to yawn, multitask, or tune others out when you’re being recorded.

Yet while it’s hard to predict what will be popular, he says, Rabbit seems to integrate popular features in an interesting way.

“It seems like it may be poised to do well in a world where more bandwidth, and more bandwidth, and more bandwidth, is available,” he says.