Why on earth would you want (say) all 10,000 comments downloaded at once?
Doesn't it make more sense to display 20 or so on each page and if you want to dig back further, a single click gets 20 more?
If it takes a couple of seconds to fetch 20 comments and there are 5,000 comments in total, that means a delay of over eight minutes before anything is displayed if you download them all at once.
If you want to display more per page, click on the header "ALL COMMENTS (n,nnn)" displayed just under the "Show more" header which expands the clip's description area. (the "(n,nnn)" part is replaced by the actual number of comments)
That gets a display of around 100 comments, not counting sub-comments on those comments, before the "Show more" button appears at the end.
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Giraffe: a ruminant with a view.