American Heritage Dictionary said: 1. 1. To transfer (recorded material) onto a new recording medium. 2. To copy (a record or tape). 2. To insert a new soundtrack, often a synchronized translation of the original dialogue, into (a film). 3. To add (sound) into a film or tape: dub in strings behind the vocal.
Since audio and video are always separate tracks conceptually (though they may be simultaneously recorded for convenience), you could then say that everything is "dubbed". AFAIK, using the word "dub" requires that an original audio track be overwritten, supplanted, or supplemented.
No. The process of adding a soundtrack to an animated film is called dubbing. As is the process of replacing the originally released soundtrack with a different language version. Those correspond to meanings 3. and 2. respectively; there's nothing about replacing required for it to be dubbing.
