Note: I haven't looked into this since 2013, so the information here may be outdated.
Summary
This piece describes an idea that used to work but now has limited potential for further involvement. I'm keeping the page up for historical interest and in case readers can find other, similar opportunities.
The original idea was to reply to comments on veg-outreach videos in order to give social support to fledgling veg*ans. It takes just a minute or two to write a comment that might make some difference to how motivated the original commenter feels to go veg*an. The current opportunity for doing this appears mostly saturated, but there may be other venues for it that I haven't yet found.
Contents
Idea
A few organizations are running efficient online veg ads linking to sites like ag-laws.info, Who's Against Animal Cruelty?, or What Came Before. In addition to viewing the video, many people leave comments like "oh my goodness! i'm officially vegan!!" or "OMG I WILL NOT EAT MEAT SINCE TODAY:(" An organizer of one of the campaigns gave me a large sampling of positive responses, all from Dec. 2011, a few of which are shown here. For even more examples of positive responses, check out the feedback page for Eugene Khutoryansky's ads.
To see the latest comments on the page, click the button with the down arrow that says something like "20,624 comments" and sort "Reverse Chronological." Of course, you can also comment on the most popular responses (and the ones shown by default) with the "Social Ranking" sort.
Facebook's changes broke notifications
In the past, one way to help support these new vegetarians was to "like" their statements and reply with suggestions on veg reading. Unfortunately, Facebook has made changes such that, when you get a reply notification in Facebook and click on it, you're not taken to your actual comment on the video but just to the video overall, making it very hard to find your original comment. This means that if you reply to others, probably they won't be able to find what you said unless they're very motivated to go looking for it.
In Nov. 2013, I did a test of the three websites, and I found that only for ag-laws.info does clicking on the Facebook notification actually open up the comment, rather than going to the home page. This means that only for ag-laws.info would this idea work right now. However, it looks like the comments there are pretty well being handled by other commenters already, so it's doubtful how much value there is to more comments, except perhaps to provide further social validation or offer different perspectives.
Example comments
In the past, before Facebook's change made replies inaccessible, I used to comment on occasion on these pages. Here are some samples of those exchanges.
Veg-eating guide
[original comment:] I'm never ever ever ever ever goin to eat another animal again! not after seening that! I litteraly started tearing up!
[my response:] That's great! Dozens of animals will be spared lives on factory farms. There are lots of guides to vegetarian eating online, like http://www.veganoutreach.org/guide/.
Supply and demand
[original comment:] I get the purpose of this video but their point is to one sided and to extreme, humans need to eat meat and other forms of protein that comes from animals and sea life. The goal and statement should be to help promote more effective and less cruel ways to slaughter animals rather then to just become a vegan. If you ask people to simply stop eating meat, then you no helping the problem but simply turning a blind eye to the situation.
[my response:] Thanks for the comment.
Veganism isn't just "turning a blind eye" because, via supply and demand, it results in fewer animals enduring lives of suffering on factory farms. I strongly support welfare improvements for farm animals as well, but such measures are not yet well implemented, so eating meat now does mean more inhumane animal treatment.
You could even argue that being vegan, or eating less meat, is a more effective stance in terms of convincing factory farms to clean up their act, because they have more to lose (i.e., your money) if they don't change. If you continue eating their products whether they reform or not, they have less incentive to listen to you.
Anyway, I'm glad we both care about this issue. :)