Deciding to rewatch old favorites depends—and this is also the case for first -time watches—on my mood. Deciding to rewatch old favorites depends—and this is also the case for first-time watches—on my mood.

https://owl.purdue.edu/owl/general_writing/punctuation/hyphen_use.html says: Use a hyphen to join two or more words serving as a single adjective before a noun: a one-way street chocolate-covered peanuts well-known author

It canould be for the feeling of nostalgia, or maybe for finding out if it still holds as one of your favorites. It could be for the feeling of nostalgia, or maybe for finding out if it still holds as one of your favorites.

I think "could" fits more with the abstractness of the topic

It can be forOne could be the feeling of nostalgia, or maybe forand another could be finding out if it still holds up as one of your favorites. One could be the feeling of nostalgia, and another could be finding out if it still holds up as one of your favorites.

I know you used "for" in the last sentence, but there is no need to repeat it throughout this one. I think it's because we're talking about reasons, not rewatches: "(the reason is) the feeling of nostalgia" rather than "(rewatching favorites is) for the feeling of nostalgia." Also, "or maybe" sounds like an alternative to the first option. What would be more natural here is to just list out reasons, which is why I made this sentence more symmetrical.

All of this aside, sometimes I rewatch a favorite, maybe one which I have rewatched multiple times before, to find something new, like some idea or concept whichthat I couldn't see before. All of this aside, sometimes I rewatch a favorite, maybe one I have rewatched multiple times before, to find something new, like some idea or concept that I couldn't see before.

So I think "that" just sounds better, but this might be why: https://www.merriam-webster.com/grammar/when-to-use-that-and-which You could also just say: All of this aside, sometimes I rewatch a favorite, maybe one I have rewatched multiple times before, to find something new, like some idea or concept I couldn't see before. and that would be perfectly intelligible

All of this asideside from that, sometimes I rewatch a favorite, maybe one which I have rewatched multiple times before, to find something new, -- some idea or concept which I couldn't see before. Aside from that, sometimes I rewatch a favorite, maybe one which I have rewatched multiple times before, to find something new -- some idea or concept which I couldn't see before.

"All of this aside" sounds like you're changing the topic. Also, "that" is better for something concrete that was previously said (e.g. those reasons).

That is one of the main reasons they are my favorite, because of their inexhaustible wealth of ideas and realizations, experiencbringing with every rewatch a new idea, a new knowledge you didn't possessunderstanding, or maybe just relearnclarifying things you thought you knew about the film. That is one of the main reasons they are my favorite, because of their inexhaustible wealth of ideas and realizations, bringing with every rewatch a new idea, a new understanding, or maybe just clarifying things you thought you knew about the film.

"experiencing" kind of makes it sound like the movies are experiencing these things, but they are letting you experience them, or they are bringing new opportunities to you. "knowledge" sounds strange in this context. "relearning things you thought you knew about the film" sounds unusual again, for a couple reasons: 1. like with "experiencing", it kind of makes it sound like the movie is the subject that is doing the verb of relearning, but rewatching the movie helps the viewer relearn. 2. "relearn" means to learn something again, but you seem to be meaning to learn something that was missed on the first watch, so it's not really relearning if it wasn't learned until the rewatch. "clarifying" would mean "improving your grasp on details," which sounds closer to your idea.

That is one of the main reasons they are my favorite, because of their inexhaustible wealth of ideas and realizations, experiencing with every rewatch a new idea, a new knowledge you didn't possess, or maybe just relearninga rediscovery of things you thought you knew about the film. That is one of the main reasons they are my favorite, because of their inexhaustible wealth of ideas and realizations, experiencing with every rewatch a new idea, new knowledge you didn't possess, or maybe just a rediscovery of things you thought you knew about the film.

"Ideas and realizations" doesn't quite sound right. I think it's because the ideas are the movie's, and the realizations are the viewer's. Also, I used "rediscovery" since it's a noun and the other two parts of the list were nouns. Lastly, "knowledge" is uncountable, so you can't say "a knowledge."

For me, rewatching favorites can be for several reasons.there could be several reasons for rewatching favorites. For me, there could be several reasons for rewatching favorites.

originally, I only added the word "done" after "can be", but I think this sounds more natural. Since your profile says C1, I think it's worth considering different ways to put together ideas for a more natural effect on the reader/interlocutor

For me, rewatching favorites can be for several reasons.there are several reasons I would do a rewatch. For me, there are several reasons I would do a rewatch.

"There are several reasons that..." is a common/natural way of putting this.