Posting or sharing short videos can be a compelling way to spread awareness of Human Trafficking. You can find many on YouTube. Here's some that I found that I thought were especially well-done.
FCAHT: Slavery Gets a MakeOver - 1.01 Minutes
Short and compelling message. Not a lot of words or information, but a link where they can find more. (Parental Note: Choral song in the background sings "what the hell are you doing" in one part of video).
FCAHT: Slave Auction -1:14 Minutes
A voice-over of an "slave auction" with modern women and men being shown. Disturbing and powerful.
(Parental Note: All people in the video are well-clothed but the auction voice-over includes sexual refernces such as "strip her down, let the gentlemen look..she's full up front and ample behind").
Modern Day Slavery - Supply Chains - 2:33 minutes
This informative video overviews slavery today with current statistics.
(Parental Note: Overall fairly safe to show. Does show a used condom.)
A21 Campaign: Natalia's Story - 4.08 Minutes
I like how this video combines one girl's story with overall slavery statistics, and ends with a hopeful message. This was made in 2011 so a few of the numbers may be outdated, but still a good general overview. This video includes a request to support the A21 Campaign.
Love146 Videos (various)
Love146 has various excellent short videos on human trafficking.
TED Talk: How to Combat Slavery by Kevin Bales - 18:32 minutes
This is the video that compelled me to start Hearts Should Be Free. Though it is from 2010 and some of the statistics have become outdated, as a general overview of the problem it is still relevant and compelling.
TED Talk: Photos That Bear Witness to Slavery - 19:18 minutes
This video shows the stories of modern slaves through photography. It is heartbreaking.