I download iTunes purchases.
It would of course be simpler to ignore this, as if with halfway decent broadband they stream fine from Apple's servers. Why bother with the time, trouble and expense of local storage and all that entails in external hard drives, etc.? Besides, that purchased elsewhere, as in example Amazon Video, cannot be downloaded. So particularly if dealing with different vendors, why not just do it the easy way and live in the Cloud exclusively?
Well, the first time the internet goes down or electricity out one is quickly informed of why not. The Cloud is a tenuous thing which can be revoked for a variety of reasons without a moment's notice. For that matter, if perchance a less than stellar internet connection at times (or peak hours) then expect lots of buffering whereas that local plays near instantly—as always.
As well, if one's credit card tied to an iTunes account should suffer a hiccup for some reason, Apple can and will peremptorily not only prevent one from purchasing new content BUT also playing anything you've already bought and paid for. You'll be dead in the water until that little financial matter is resolved to their satisfaction.
Which brings us to the vagaries and lifespans of corporations. Just how many do you know who have been in business for 400 years, even 100 years, 50? Yet chances are long before one's favorite vendor implodes it will have changed various policies to one's disfavor and possible detriment. With anything in the Cloud one is placing a bet on how long current conditions will last.
In example, it is kind of Apple—if perhaps a major oversight—to in effect grant lifetime free server space for all the multi-GB of media one has purchased through them, somehow overlooking how much they like to charge for a fraction as much space for other uses. This munificence may change in time, or perhaps without notice tomorrow.
Bottom line is that not in one's hand is not entirely owned. Or, put another way, possession is 9/10's of the law. If having paid good money for a favorite movie one really likes and doesn't want to lose, well . . .
On the other hand, just how many terabytes of data does one want to deal with in downloading, filing away, backing up, etc.? Then also in considering necessary hardware to view it, as in encoding standards change, and that with Apple's DRM will require relevant hardware to use, unless that ripped out. But still, floppy discs anyone?
Then, too, when is enough enough? Is SD okay, or 1080p the pinnacle of satisfaction. Or will that once fine in 1080p be viewed as now amiss when 4k, 8k or some other more the standard? 35mm film presents a lot of data possibilities.
Maybe just download and save that one truly treasures. Or possibly the whole enchilada. In either event perhaps reflecting on just how long one intends to live, or how often one will be returning to any particular movie or TV series.
But if the Cloud, then enjoy the ease and simplicity. Only never, ever trust it absolutely.