I've had very good success with Reddit. I just got over 100 subs (not views, subscribers) from a Reddit post I made 2 days ago!
I would imagine the reaction to making video posts on Reddit is very niche-dependent. My channel is about low carb cooking. There are several subreddits specifically about low carb recipes. So, as long as I follow the specific posting rules of each subreddit I post in, and the post is on topic, it generally gets good traction. I posted my latest video (it's about testing blood sugar response to different artificial seeeteners) two days ago to one of the low carb forums and I've gotten about 600 views and over 100 subscribers from it already.
If you're respectful on Reddit and genuinely following subreddits rules, I think it can be very positive. Interacting on other posts in the subreddits also helps, because the other posters can see your previous posts. If you have zero post history and come in to a subreddit and start posting random videos, it's not gonna go over well because you just look like a YouTube spammer *trying* just to get views, rather than participating in their actual community of readers. And they will retaliate, and rightly so.