I really like the accent! At first I found it extremely odd but it's grown on me so much over time it's honestly the main reason I watch his videos now.

It seems really unusual to me too. I've got Czech relatives and have visited several times as a tourist but seem to have missed out on hearing this accent somehow (probably as I've barely left Prague).

It sounds normal + imitation of 'American YouTuber' to me: the drawn out vowels being common in many US accents anyway, and then the 'let's fiind oooouuuutt' sort of YouTuber affectation that's itself an imitation of a certain sort of TV presenter I suppose - Jeremy Clarkson for example.

To my native Czech ear, this sounds like the English accent of a native Czech speaker who learnt English primarily by reading, back when English audio wasn't readily available.