Yes the streaming services don't keep films and series forever. The iPlayer will keep some films for 28 days. On Amazon Prime we've watched the series called The Expanse but they don't have it anymore it's gone to Netflix which we don't have and probably never will, can't record those.
I'm still waiting for a couple of "film noir" which I lost in the hard drive crash to come round again. one is this. Starring Alan Ladd and Veronica Lake. The problem is obviously, because they're in monochrome. Twenty years ago, Alan Whicker suggested doing a new series of "Whicker's World," where he would revisit the places he'd recorded during the first series, twenty years before, of which they could show clips and make comparisons. Their immediate reaction, he said, was to say, "No, viewers don't like anything in black and white." "Talking Pictures" show a lot of old films in monochome, that I consider worth watching. But it's a pain trawling through the listings in the hope of finding what I'd like to see again. I like the thirty-year old comedy film "Mannequin," with Kim Cattrall, which does get shown now and again. It's almost a musical. It's a re-make of this starring Ava Gardner and Robert Walker A film with a better ending, which I have on DVD. But I doubt if it will be shown, although they have I think, or maybe another minor channel, shown another Robert Walker film, "Strangers on a Train,"