GoodTimesWithScar’s /æ/-tensing. The phenomenon is messy, as it depends on the dialect and the phonetic environment of the vowel, but before /n/ most speakers of North American dialects would realise /æ/ like he did, [ɛə̯]. Another example of the same phenomenon would be Etho, who’s from Canada.
GoodTimesWithScar’s regressive nasalisation. The video transcribes it accurately as ranging from the start of the diphthong, not just near the end; that hints that, at least in his dialect, vowel nasalisation is already phonologised.
MumboJumbo’s [h]. I think that he’s being cheeky and playing with how others pronounce the word; do note however that /æ/-tensing is not common in the UK, where he’s from.
A few things that caught my attention in this: