Photo of Mandy Moore & Milo Ventimiglia in 'This Is Us' pilot, by Ron Batzdorff

In just 48 hours, NBC's upcoming dramedy This Is Us has become the fall's most buzzworthy new show, breaking a Facebook record for most views for a new show trailer during the week of upfront presentations.

As the networks this week continue making their pitches to advertisers with their fall slate of programming, the trailer for This Is Us has racked up more than 15 million views (not counting YouTube viewers), surpassing the CW's 2015 trailer for Legends of Tomorrow (4 million views).

By comparison, the trailer for NBC's new drama Timeless, which had previously been at the center of the network's 2016-17 plans, has only attracted 4 million views, with both clips having been released simultaneously on Sunday (May 15).

Written and executive produced by Crazy, Stupid, Love writer Dan Fogelman, This Is Us follows an ensemble, some with the same birthdays, whose life stories begin to intertwine in curious ways.

The series stars Mandy Moore, Milo Ventimiglia, Justin Hartley, Chrissy Metz, Sterling K. Brown and Susan Kelechi Watson.

The emotional trailer (which includes Ventimiglia's bare buttocks) can be seen below.