How do social media companies like twitter or youtube not run out of space for posts?
I know memory is fairly cheap but e.g. there are millions of new videos on youtube everyday, each probably few hundred MBs to few GBs. It all has to take enormous amount of space. Not to mention backups.
That response is almost 10 years old and completely outdated. I've designed and maintained a national media service and can confirm that on the fly transcoding is both cheaper and easier. It does make sense to store different formats of videos that are popular at the minute but in the medium to long term streams are transcoded.
I think you might be underestimating how many users YouTube has! According to this, 720,000 hours per day are uploaded versus 1,000,000,000 hours are watched per day!
No assumptions about specific usage. Just that at a certain point or in certain scenarios (that I’m sure YouTube’s engineers fully understand), there’s a point where one becomes more cost effective than the other.
Those are pretty incredible numbers though, wow. The scale of that usage is insane.