Some of them don't allow vid responses? How do you know that? Once you post a response? Those no response vids have to be in some very small minority...
and you'd need quite a lot of videos for auto response posting since a video can only be response to one another video.
You better copy the tags of a new viral video and your video gets display on the right side of that video so people will click on it.
Very simple, look at the video how many vid respondes they already have..
If it's about 10+ vid responds.. you could try it.. if you get one with no responds at all and high view count.. you beter cancel that out.