I think this has been mentioned before, but to reiterate.
Most music channels don’t have a designated team (of course, check their page to see if they say anything). So you’re usually free to segment and/or translate music videos as you like. You can always message a manager or mod to be sure.
As for dramas. You have two options with finding projects. You can either search up dramas you’re interested in (or browse around until you find one), and message the manager of moderator about helping. They’ll get back to you with a yes/no and some details or whatever.
Or you can just check the project category on the forum and see if anyone’s looking for segmenters. I’m also compiling a list of projects that I see here that need segmenters here, so you can look through that too.