You can, yeah, do a reaction video type format, indeed wherein you put a small version of the original video in one side, focused on you and your reaction in the rest of the screens. Then pause the video when you do commentary etc. I do a similar niche so I'm still learning.
What I understand...
What helped me grow my channel is to look at trending topics for your niche or channel type. Like, if you do song covers, looking at say the Itunes New Songs chart or YouTube trending can be a good starting point on a song you may want to cover, that people are searching for now.
The borders are definitely okay. I'd click the thumbnail if it ever was shown to me, because these are the type of videos I want to see as it's different from what I'm normally shown.
And also, i want to know what happens after they jump.
Yeah, I agree it is challenging to get our videos discovered in YouTube. The Keyword Explorer and the SEO studio tools of TubeBuddy really helped me finds topics that are easy to get views for my niche and also help me make my videos more discoverable via the meta data.
When you're starting, it can be hard to get viewers. Youtube can take time to give impressions of your video, since they don't have information about you and your videos yet. I think of it like "I dont have a credit standing" with YT yet.
But, just keep pushing and just posting videos. If you...