On youtube I found the senior battle, but I can't find the junior and ones. Pokemonvgc.com brings you to pokemonchampionship.com. They just give you tiny clips of the battles.
There are quite a few videos on YouTube from various regional finals, worlds might be among them somewhere:
Apart from that, I don't know. If they are not on the official web site then maybe no one recorded them. The YouTube ones are all amateur footage.
How to change your username
How to add a user avatar
Why was my post hidden?
Flags vs Downvotes
Official PokemonDb League
Type a Pokemon name, type, move or ability to see instant results.