Anyone ever tried this for carrying a car seat?

My DS2 is pushing 20lbs and is getting really hard to carry in his car seat while I'm also carrying DS1 who is currently 30lbs.

I'm trying this tonight!

http://www.msn.com/en-us/video/lifestyle/watch-the-car-seat-carry-hack-that-is-blowing-parents-minds/vi-BBDmnoK