I`d like use yellow, black and white, to feel energetic, vibrant yet no too yellow, no to be interpreted as aggressive.
The style I`m imagining [with my limited imagination] is something flat [Ealuxe like, Search Youtube], something magazine like could work as well if presented right, I appreciate in this regard the branding on Cycling Weekly [ Youtube channel] and Wirecutter [ Review Website].
The piece should be coherent, I`d like to give the impression of an established media brand directly, super clean.
It is very important to weight thumbnails well and if possible offer multiple variants for these colors, typography, their balance, coherence is key.
Proposed Transition Pieces, Coherent with Thumbnails; example of video to be nestled the channel https://goo.gl/gSbjpE
EDIT1: "Yellow Reviews" will be the name of the channel, at this point we have no content or channel to showcase. It will mainly contain product reviews.