Question on MIT Sloan Optional Essay

I was wondering the same thing, but hadn't seen the application before that info session I attended to ask it that day.

Sloan is having an online webinar next week, so you got a chance to ask live and get an immediate response:
https://applymitsloan.mit.edu/register/MBAChatAug262015

(I literally received the invite to that chat the second I went to respond to your reply.)

I have a concrete answer to your question after attending the Sloan Ambassador Program event today. Adcom said that additional portion about yourself, whether in writing, a video, blog post, etc, must be read within around a minute, so it can't be too long. You can basically separate this portion from actual statements about your gaps all the same way with a line space in between to separate them. For example, you possibly spend 2 sentences talking about a low GPA, then leave one line break between that and your paragraphs about yourself or a link to your blog post or link to a video or whatever medium you have that in. If it's a link to something online, obviously let them know what you are trying to show them before presenting the link.