This is so cool. 1Hope is a United Church-related group of outreach ministries in Winnipeg. 

From the YouTube post:

Hope and harmony came together in Winnipeg's core when hundreds of people gathered for a Flash Mob to raise awareness for 1Hope Winnipeg.

The Flash Mob took place at Portage Place over the lunch hour and featured local hip hop artists Sadie and Bubba B, who teamed up to sing 'My World' - a song they've gifted to 1Hope Winnipeg. You can purchase the song at http://1hopewinnipeg.com/myworld/

For more information about 1Hope Winnipeg and how you can reach out to Winnipeggers in need, please visit the website and donate.

Help create change in your city - one step at a time. Together, we can give hope.