Depends on rep.
If you're mostly playing cover tunes in a guitar-based rock or blues band, many of those songs were written on guitars in guitar-friendly keys, which fit on a 4-string bass because of how the tuning aligns.
Outside that world, they're used a lot more. Pop for instance is more often composed either on keyboards/synths, so it has no reason to hold to guitar-friendly keys - so you're more likely to see Eb's, D's, C's, and B's. Jazz often features wind-instrument-friendly keys that include Eb's or go down to D, or else use non-open-string tonality so having more notes in a given position is helpful. Musical theatre goes for singer-friendly keys, which are all over the place. Heck, if you're reading sheet music sometimes a composer gets confused about the range of the instrument (some notation programs consider 5-string low-B tuning normal for a bass guitar, and C-extension notes normal for an upright).
As for the examples you call out - I can't say why those specific guys aren't using them on those specific videos. Flashy-riff showoffs tend to favor higher notes for any number of reasons, even on a 4-string, and I suspect if they had a high-C they'd use it. Maybe the key they chose to play in that day just doesn't need the fifth-string. Maybe they're in the "35-inch thumbrest" school of thought but actually like the thumbrest.
But at the end of the day, it's individual circumstance and preference. If you don't feel like you need a 5+-string, don't buy one, but keep in mind other people wind up on different sides of that decision. There's not a right answer, or a wrong one.
((NB: I play low-B 5's pretty exclusively, because I mostly play in jazz and musical theatre; the notes show up enough that I find it useful. There are plenty of people I know in the same genres that don't make the same decision. To each their own.))