how to play an mp4 from msft onedrive
how to play with Safari an mp4 file posted on msft onedrive
MacBook Pro (15-inch Early 2011), Mac OS X (10.6.8)
Your Mac must be running v10.7 or later to use Michrosoft OneDrive > http://windows.microsoft.com/en-us/onedrive/system-requirements
So if your Mac is running v10.6.8 as noted from your post, you will have to upgrade to v10.7 Lion.
OS X Lion - Technical Specifications
v10.7 Lion is available for purchase from the Apple online store > OS X Lion (10.7) - Apple Store
Very important to read this user tip prior to upgrading from Snow Leoaprd > Upgrading to 10.7 and above, don't forget Rosetta!