Starter accounts are a great way to play for as long as you want to decide if World of Warcraft is for you.
However, one thing to watch out for is that for YouTube to allow you to monetise your video, it has to have a running commentary over the entire video, not just snippets or you silently playing the game.
One nice feature: If you have a lapsed WoW account that has enough gold in it to purchase a token, you can do that right from the character select screen.
World of Warcraft is a big game (70 GB so downloading will take a while on even the fastest connections.
WoW Tokens are currently fluctuating in price between around 80,000 and 100,000 gold, so it should take you around 4-5 hours of farming to earn a token.
A bundle of 50 loot boxes costs 40 plus tax, so Overwatch pays out loot-box rewards worth about sixty cents for every hour you play.