@Freso- that is a lot of thought. In order...
1) Agree with that statement, as long as the video qualifies as a video by specification, content, morals or any other opinions on the actual content should not matter. Just like explicit lyrics in audio, it is just labeled as such, it is not excluded.
2) True. For the purposes I proposed, cover art would be needed, at least as a reference, or the usefulness would be reduced and possibly bypassed for the current options. Agree on adult content, the images are more the concern over titles.
3) Clips is way out of scope from my original thought, but can be accommodated. TVDB does not do this really, but IMDB and TMDB do, short film or video flags would apply. A series name can also be applied, like the Star Wars series as an example. Would that satisfy your interest on this point?
4) That would be great and easy I think. In the "crew" section, or whatever it may be called, you could add as many roles as you like and assign as many people to those roles as you like. We could define core roles, like director, writer, producer, etc, but there does not have to be any limit on who can be added.
5) Yes, agreed. Although I typically see music videos in a class of its own from video and audio, I think it could fit in just fine. The alternative would be something like... MovieBrainz, TVBrainz, ClipBrains, VideoBrainz, ShortFilmBrainz, etc.We could separate, or work to be all inclusive of video. Thinking about BookBrainz, it is only books, not flyers, magazines, comics, etc correct? I wonder how we decide this. Is BookBrainz a "printed on paper item" listing or a listing of "books"? Would VideoBRainz be a listing of anything with video, or a clearer definition of a video similar to now MusicBrainz uses bootlegs, where a bootleg could be excluded even though it has full artwork and pressed CDs, but it is not really available sort of thing. What qualifies the video content to be included?
6) I will be light on this one, because I somewhat disagree on parts. MusicBrainz does not do well with fitting my needs, being a person who collects music, plays music, performs music, etc. It is great as an encyclopedia type reference, but near useless for tagging to me. Reason is when I make digital files, I do not need or care to tag what CD by what label and what barcode the digital copy came from, I want to tag the "12 track deluxe release". MB is by far the best I have used, which is why I support it. The reason is not due to the fact that I can actually use the data, it is that I like the data. I tag myself in MP3TAG, then import and modify it to how MB wants it, then leave it be. Personally, I do not feel the data is "data-centric" I say this because, for example, if it was data-centric, we would differentiate between a MP3 release and a M4A release. I also think the database structure is missing a tier of data in the release area that moves it away from being data-centric. I feel it is less object orientated than it could be, making it less data-centric than it could be. Just the opinion of one person, not complaining.
I think you are correct, it cannot be designed for one use only, because even that one use will change over time. Just like in MB, the lacking of structure for digital releases will show its ugly head at some point, but it was designed around physical releases which is clear as the only thing not physical in the medium options is "Digital Media", the rest is all physical variations. But we would also need to consider that data is only valuable if it can be used. If no one can use the data, demand and draw lack and the marketplace will evolve to satisfy its own needs. Meaning, someone else will provide a solution to meet real needs, even though its quality will likely be lesser. Give and take, the exact reason that TVDB is number 1 to its alternatives... it fits the need of the consumer, but is less than perfect in many ways.