If a person death is reported from any friend or family members, and ask their loved one's timeline to memorialized, Facebook will first change the privacy of that person to only friends, second their will be a look back video of on his Timeline.
Before you continue to request look back video you can simply Add the dead person to Facebook Memorialized
This option gives you and your family to remember the loved one's by their profile and photos. If you have lost someone who have a Facebook profile than you can simply request to Facebook by following steps below:
Step 1: You will need request to Facebook from here.
Step 2: Now fill up the details of the person Full name, Email Address, Timeline Profile Link,
Step 3: If you have enabled the memorialized for the person than choose Yes, if didn't than Choose No.
Step 4: Your full name, email address and if possible give additional details and click Send.