In TubeAssist, when you share a video with another user, they receive an email with the video that you shared. Many users will watch this video, and if they like it take a look at and subscribe to your channel. Since TubeAssist shares over 100 videos per day, this means that over 3,000 people per month will see your video.
Many of these users will also click to check our your other videos too. As the days go by, your views, subscribers, comments, etc. will keep going up. You aren't purchasing subscribers so you won't see 10,000 new subscribers over night, but unlike purchased subscribers, they are real people who will view and interact with your channel.
Playlists are an even better way (inside and outside of TubeAssist) to get users to watch more of your videos. If a person watches the first video in a playlist and like it, they are more likely to go on and watch future videos as well. This is one of the suggestions in the YouTube Creator playbook to get more views.