Due to recent YouTube changes, this isn't possible anymore.
The way we share videos with a user is by commenting on one of their videos. Right after we leave the comment, we then delete it. The user gets emailed, but no comment is left behind long term. So it works like a true share video.
The advantage to this is that no comments are left behind long term. Most users prefer this because there isn't a risk of the comment being flagged as spam. The downside to this is that there is no way to verify the videos are being shared, other than by watching for an increase in views, subscribers, etc. for your channel.
If you really wanted to test the process, you could always do the following:
1. Create a new YouTube channel (different than the one linked to TubeAssist).
2. Upload a video to that channel.
3. Leave a comment on that video.
4. Create a new Share Video campaign in TubeAssist. Enter the search phrase as @your_new_channel_username
If you do this, your new channel should be gathered and you should get emailed when a comment is left on your video. Please keep in mind that TubeAssist will never send to the same YouTube user twice from the same TubeAssist account so this will only work once per new channel you create.
If you have any questions about this, please let us know.