No idea who discovered those great youtube tricks as first person in the world, but never mind in this case. For such well-known old tricks which were only forgotten for awhile until someone, or many, remembered to try them again, all attempts to identify Who-dunnit-first will go in circles anyway. Like UA-googlebot in general, or anti-polymer key in youtube-URL. In that mentioned long REDDIT topic the earliest UA discoverer seems to be one of the addon-authors, Mirza, a few weeks ago. But whatever, such great tricks should be spread, and the tinkerers among us will surely remember sooner next time to try pesky sites with UA googlebot :-)
What a disaster that such useragent tricks will probably fail soon on many main sites, since all big browser makers last year happily announced to transfer those same data -plus more- in future builds only in stealth and unfakeable ways. Much deeper under the hood, requiring modern browsers and new server request methods, so finally all older engines can be identified 100% and get blocked much easier, grrr.
But origin or not, since you like to spread such user tricks, here's a tiny, crucial yt-fix which could use more spreading too (while it still works...)
Figured it out myself last year after long struggling due to old browser probs, where that pesky "Show more" button for video description is broken since years. It's so basic that probably a bunch of other people found it on their own too, no big feat. Nevertheless haven't seen it posted elsewhere yet, and it's not mentioned in that long reddit-topic either although the prob was discussed there. Looks like semi-modern browsers now suddenly have the same prob, video description cropped and button broken, description remains hidden. But installing a whole addon or a javascript file user.js just to fix this button seems overkill to me. So this fix could please be spread a bit more too...
This is just a tiny userCSS for youtube CLASSIC view, which makes the complete youtube description text visible at page load. No need to click that "Show more" button anymore. Minor catch: this useless button still remains visible too, looks confusing, but can live with it ;-P
Can be added to slightly older Mozilla browers e.g. in current profile, in file /chrome/userContent.css
@-moz-document domain(youtube.com) {
#watch-description-text {height: auto !important; max-height: none !important;}
}
While at it, a reminder of yet another crucial UA trick: to get .3gp movies with TINY file size.
Posted by a kind soul (thanks!) awhile back. Only useful for people desperate for extremely tiny filesize, due to bandwith probs or limited disk size, no matter how horrible the quality. Even if those videos have almost stamp size: UA Mobile IPAD still gets those offered, and the page source still contains direct download links too (itag ":36,")
example
Mozilla/5.0 (iPad; CPU OS 6_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10A403 Safari/8536.25