We've seen the extensive photo gallery of next week's much-anticipated episode of Grey's Anatomy, "If/Then." Now we have your first video sneak preview ... the first 11 minutes' worth to be exact!

As Meredith puts her adorable adopted daughter Zola to bed and falls asleep, she begins to wonder ... what if her mother Ellis had never had Alzheimer's and she'd had loving, supportive parents?

The reverberations of a happy Meredith Grey completely alter the world of Seattle Grace as we know it. What if she had never met Derek in that bar and he had never separated from Addison?

What if Callie and Owen had become a couple long before she met Arizona Robbins? And what if Bailey never evolved from the meek intern she once was? We'll find out in a very special episode.

Watch the first portion of it below and see what you think ...

Steve Marsi is the Managing Editor of TV Fanatic. Follow him on Google+ or email him here.