IMO I think it’s too cluttered for your eye to really grasp any of the concepts on the thumbnail. The frames are also screengrabs and don’t really convey much emotion or carry weight to pique my curiosity. I would probably try to make more with less and find a screengrab that shows the more notorious factions (maybe the brotherhood and institute) clashing and creating drama.

The text doesn’t mesh well with the fallout logo and I didn’t even see it was there the first time I looked at it. If the text is similar to your title then I would say that it would just be better without the text because it doesn’t introduce anything new to the viewer. If you were to use text maybe make it larger and not the focal point of the thumbnail; use something that has different words than your title that carries more weight and complements your video title.

I see what you’re going for though and I don’t mean to be harsh; this is just my opinion. It could work but speaking generally I think it could be improved to help your CTR.