The extension technically works as described. However, there are a few annoying issues that make it hard to use sometimes:

1. Sometimes, a video will be posted multiple times to the same subreddit. This extension seems to only grab one result per subreddit. This is a problem because more often than not the result this extension grabs is not the most popular thread for the video on that particular sub. In other words, you watch the video, and you get the r/videos thread with 12 upvotes and 3 comments, then you head over to reddit and find the same video posted on the front page with 1000+ upvotes and 100+ comments. This extension should either show the most upvoted thread per subreddit, or show all the threads for a subreddit, instead of choosing one and often times getting it wrong.

2. Sometimes this extension says there are no results on reddit, even though there definitely are. It's funny that the author chose a Game Grumps video as an example, since that subreddit has a bot that automatically posts every Game Grumps video to their subreddit, meaning every GG video should have a result, yet some of their videos will show no results despite a thread definitely existing on reddit. Same thing happens with Rooster Teeth/Achievement Hunter/Let's Play videos, which also have a bot auto-posting their vids to the RT subreddit. I've lost track of how many times I've watched a video with supposedly "no results", and headed over to that channel's subreddit to find a thread for the video on the front page.

I imagine both of those issues might have something to do with the many different ways you can link to a YouTube video on reddit (ex: https://www.youtube.com/watch?v=dQw4w9WgXcQ -OR- https://youtu.be/dQw4w9WgXcQ). The author needs to solve these issues for this extension to be perfect.