Halacha says one can not listen to “music”. Halacha does not say one can not have a website that streams music. I don’t think lifnei iver applies when A)there are many definitions of halachic “music”, and B) the person looking for music will get worse music elsewhere just as easily. As to movies and shemiras einayim, I was told by someone who I consider to be on a high level of prishus especially in regard to shmiras einayim that shmiras einayim is subjective. If a person is desensitized to a level of pritzus for whatever the reason, then a relatively smaller amount of pritzus would not be assur to look at. My own thoughts – Obviously one must work on oneself to increase sensitivity to eventually reach or strive for the level of etzba k’tana. Also, if one let themselves fall, and ruined their own sensitivity, if they were on the level where they should have been able to stop themselves and didn’t, they are liable for the level that they are currently on. That doesn’t mean it is assur for them now on a subjective level. This is the famous nekudas habechira concept(see michtav me’eliyahu 1). Rav Dessler writes that a highwayman who usually kills his victims after he robs them, and one time decides to rob without killing, can get schar for the objectively wrong act of theft. Moreover, that could be the purpose of his life, to get to that level. Similarly while objectifying an etzba ktana is objectively wrong, on a subjective level a person must identify their own level and work on increasing it. A person is not liable for anything above the range that they are in (provided they didn’t negligibly put themselves there).
Specifically with shmiras einayim where the issue is hirhur, one can easily be desensitized to many things.
As such, no one can say anything about any other person and al tadin es chaveircha ad shetagia limkomo (avos).